Cisco GSS Configuration Guide (Software Version 1.1) - Configuring Answers and Answer Groups [Cisco ACE GSS 4400 Series Global Site Selector Appliances]

Table Of Contents

Configuring Answers and Answer Groups

Configuring and Modifying Answers

Creating a VIP-Type Answer

VIP Answer—ICMP KeepAlive

VIP Answer—TCP KeepAlive

VIP Answer—HTTP HEAD KeepAlive

VIP Answer—KAL-AP KeepAlive

Creating a CRA-Type Answer

Creating a Name Server-Type Answer

Modifying an Answer

Suspending an Answer

Reactivating an Answer

Suspending or Reactivating All Answers in a Location

Deleting an Answer

Configuring and Modifying Answer Groups

Creating an Answer Group

Modifying an Answer Group

Suspending or Reactivating an Answer Group

Suspending or Reactivating All Answers in an Answer Group Associated with an Owner

Deleting an Answer Group

Where to Go Next

Configuring Answers and Answer Groups

This chapter describes how to create and configure GSS answers and answer groups. It contains the following major sections:

•Configuring and Modifying Answers

•Configuring and Modifying Answer Groups

Configuring and Modifying Answers

In a GSS network, the term answers refers to resources that respond to content queries. When you create an answer using the primary GSSM, you are simply identifying a resource on your GSS network to which queries can be directed and that can provide your user's D-proxy with the address of a valid host to serve their request.

Examples of GSS answers are:

•VIP—Virtual IP (VIP) addresses associated with an SLB such as the Cisco CSS, Cisco CSM, Cisco IOS-compliant SLB, LocalDirector, a Web server, cache, or other geographically dispersed SLBs in a global network deployment.

•Name Server—A configured DNS name server on your network that can answer queries that the GSS cannot resolve.

•CRA—Content routing agents that use a resolution process called DNS race to send identical and simultaneous responses back to a user's D-proxy.

Once created, answers are grouped together as resource pools from which the GSS, using one of a number of available balance methods in a DNS rule, can choose the most appropriate answer for each user request.

In addition, once the query is passed to the answer, intelligence on that resource can be applied in choosing the best host. For example, a request that is routed to VIP associated with a CSS is evaluated by the CSS after it is received and directed to the most suitable host managed by that CSS.

In addition to specifying a resource, each answer also provides you with the option of specifying a keepalive for that resource a method by which the GSS can periodically check to see if the resource is still up and running. The keepalive monitoring method available to you varies with the resource type, as explained in this section.

This section includes the following procedures:

•Creating a VIP-Type Answer

•Creating a CRA-Type Answer

•Creating a Name Server-Type Answer

•Modifying an Answer

•Suspending an Answer

•Reactivating an Answer

•Suspending or Reactivating All Answers in a Location

•Deleting an Answer

Creating a VIP-Type Answer

The VIP-type answer refers to a virtual IP address (VIP) associated with an SLB device such as a Cisco CSS or CSM. When the GSS receives requests for content that is managed by an SLB, the GSS returns an A-record containing the VIP of the SLB that manages that content.

When configuring a VIP-type answer you have the option of configuring one of a variety of different keepalive types to test for that answer. For a KAL-AP keepalive, it is necessary to configure shared keepalives before configuring your answer. Refer to Chapter 6, Configuring KeepAlives for more information on creating shared keepalives.

Note Once an answer is created the Answer type cannot be modified (for example, from VIP to CRA).

To configure a VIP-type answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (Figure 7-1).

Figure 7-1 Answers List Page

3. Click the Create Answer icon. The Creating New Answer detail page appears (Figure 7-2).

Figure 7-2 Creating New Answer Details Page

4. In the Type field, click the VIP option button. The VIP Answer section appears in the details page (Figure 7-3).

Figure 7-3 Creating New Answer—VIP Details Page

5. In the Name field, enter a name for the VIP-type answer you are creating. Specifying a name for the answer is an optional step.

6. From the Location drop-down list, select an GSS location to which the answer corresponds. Specifying a location for an answer is an optional step. For details about creating a location, refer to Chapter 3, Configuring Resources.

7. In the VIP address field, enter the VIP address to which the GSS will forward requests.

8. Choose from one of the five keepalive types for your VIP answer:

– None—Does not send keepalive queries to the VIP. The GSS assumes that the VIP is always alive.

– ICMP—Sends an ICMP echo message (ping) to the specified address. Online status is determined by the response received from the device, indicating simple connectivity to the network.

– TCP—Sends a TCP handshake to the specified IP address and port number of the remote device to determine service viability (three-way handshake and connection termination method), returning the online status of the device.

– HTTP-Head—Sends a TCP format HTTP HEAD request to an origin web server at a specified address. Online status of the device is determined in the form of an HTTP Response Status Code of 200 (for example, HTTP/1.0 200 OK) from the server as well as information on the web page status and content size.

– KAL-AP—Sends a detailed query to the Cisco CSS or CSM to extract load and availability. Online status is determined when these SLBs respond with information about a hosted domain name, host VIP address, or a configured tag on a content rule.

The following procedures describe how to configure the properties for the individual VIP keepalives. The default values used for each of the VIP keepalives are determined by the values specified in the Global Keepalive Properties details page.

–VIP Answer—ICMP KeepAlive

–VIP Answer—TCP KeepAlive

–VIP Answer—HTTP HEAD KeepAlive

–VIP Answer—KAL-AP KeepAlive

VIP Answer—ICMP KeepAlive

To define the ICMP keepalive for your VIP answer, see Figure 7-4 and perform the following steps:

Figure 7-4 Answer Details Page—ICMP KeepAlive VIP Answer

1. The VIP Address check box is automatically checked to instruct the GSS to send an ICMP echo message (ping) to the VIP address of the remote device and determine online status. If necessary, uncheck the VIP Address check box and select an ICMP-type shared keepalive from the Shared ICMP Keepalive drop-down list.

2. If the ICMP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section:

–In the Number of Retries field, specify the number of times the GSS retransmits an ICMP echo request packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The range is 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value.

–In the Number of Successful Probes field, specify the number of consecutive successful ICMP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The range is 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value.

Note For background details on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section.

3. Click the Submit button to save your ICMP keepalive VIP answer. You return to the Answers list page.

VIP Answer—TCP KeepAlive

To define the TCP shared keepalive for your VIP answer, see Figure 7-5 and perform the following steps:

Figure 7-5 Answer Details Page—TCP KeepAlive VIP Answer

1. The VIP Address check box is automatically checked to instruct the GSS to send a TCP keepalive to the VIP address of the remote device and determine online status. If necessary, uncheck the VIP Address check box and choose a TCP-type shared keepalive from the Shared TCP Keepalive drop-down list.

2. In the Destination Port field enter the port on the remote device that is to receive the TCP keepalive request. The port range is 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value.

3. If you enabled the VIP Address check box, specify the TCP keepalive connection termination method:

– Default—Always use the globally defined TCP keepalive connection method.

–Reset—The GSS immediately terminates the TCP connection by using a hard reset.

–Graceful—The GSS initiates the graceful closing of a TCP connection by using the standard three-way connection termination method.

4. If the TCP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section:

–In the Number of Retries field, specify the number of times the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The range is 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value.

Note When using the Graceful termination sequence, there are two packets that require acknowledgement: SYN and FIN.

–In the Number of Successful Probes field, specify the number of consecutive successful TCP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The range is 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value.

Note For background details on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section.

5. Click the Submit button to save your TCP keepalive VIP answer. You return to the Answers list page.

VIP Answer—HTTP HEAD KeepAlive

To define the HTTP HEAD shared keepalive for your VIP answer, see Figure 7-6 and perform the following steps:

Figure 7-6 Answer Details Page—HTTP HEAD KeepAlive VIP Answer

1. The VIP Address check box is automatically checked to instruct the GSS to send a TCP format HTTP HEAD request to the web server at an address you specified and determine online status. If necessary, uncheck the VIP Address check box and select an HTTP-type shared keepalive from the Shared HTTP HEAD keepalive drop-down list.

2. In the Destination Port field enter the port on the remote device that receives the HTTP HEAD-type keepalive request from the GSS. The port range is 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value.

3. In the Host Tag field, enter an optional domain name that is sent to the VIP as part of the HTTP HEAD query in the Host tag field. This tag allows an SLB to resolve the keepalive request to a particular website even when multiple sites are represented by the same VIP.

4. In the Path field, enter the path that is relative to the server website being queried in the HTTP HEAD request. If you do not specify a default path, the GSS uses the globally configured value. For example: /company/owner

5. If you enabled the VIP Address check box, specify the HTTP HEAD keepalive connection termination method:

– Default—Always use the globally defined HTTP HEAD keepalive connection method.

–Reset—The GSS immediately terminates the TCP formatted HTTP HEAD connection by using a hard reset.

–Graceful—The GSS initiates the graceful closing of a TCP formatted HTTP HEAD connection by using the standard three-way connection termination method.

6. If the HTTP HEAD global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section:

–In the Number of Retries field, specify the number of times the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The range is 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value.

Note When using the Graceful termination sequence, there are three packets that require acknowledgement: SYN, HEAD, and FIN.

–In the Number of Successful Probes field, specify the number of consecutive successful HTTP HEAD keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The range is 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value.

Note For background details on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section.

7. Click the Submit button to save your HTTP HEAD keepalive VIP answer. You return to the Answers list page.

VIP Answer—KAL-AP KeepAlive

To define the KAL-AP shared keepalive for your VIP answer, see Figure 7-7 and perform the following steps:

Figure 7-7 Answer Details Page—KAL-AP Keepalive VIP Answer

1. From the KAL-AP Type drop-down list, select the format of the KAL-AP keepalive query. Your choices are:

– KAL-AP By Tag—Embeds an alphanumeric tag associated with the VIP in the KAL-AP request. The tag value is used to match the correct shared keepalive VIP, thus avoiding confusion that can be caused when probing for the status of a VIP that is located behind a firewall network address translation (NAT).

– KAL-AP By VIP—Embeds the keepalive VIP address in the KAL-AP request. The KAL-AP queries the keepalive address to determine online status.

2. If you chose KAL-AP By VIP, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list.

3. If you chose KAL-AP By Tag, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list, then enter a unique alphanumeric value in the Tag field. This is used as a "key" by the CSS or GSSM that matches the KAL-AP request with the appropriate VIP.

4. Click the Submit button to save your KAL-AP keepalive VIP answer. You return to the Answers list page.

Creating a CRA-Type Answer

The content routing agent (CRA) answer type relies on content routing agents and the GSS to choose a suitable answer for a given query based on the proximity of two or more possible hosts to the requesting D-proxy.

With the CRA answer type, requests received from a particular D-proxy are served by the content server that responds first to the request. Response time is measured using a DNS race, coordinated by the GSS and content routing agents running on each content server. In the race, multiple hosts respond simultaneously to a request. The server with the fastest response time (the shortest network delay between itself and the client's D-proxy) is chosen to serve the content.

The CRA answer type is designed to work with the GSS when the boomerang balance method is selected for a DNS rule (utilizing the Boomerang Server component of the GSS).

Closeness is determined when multiple hosts reply to the requesting D-proxy simultaneously in what is referred to as a "DNS race." The GSS coordinates the start of the race so that all CRAs initiate their response at the same time. The first DNS reply to reach the D-proxy is chosen by the name server as the host containing the answer.

Note Once an answer is created the Answer type cannot be modified (for example, from CRA to VIP).

To configure a CRA-type answer type:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1).

3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 7-2).

4. In the Type selection field, click the CRA option button. The CRA Answer section appears in the details page (Figure 7-8).

Figure 7-8 Creating New Answer—CRA Answer

5. In the Name field enter a name for the CRA-type answer being created. Specifying a name for the answer is an optional step.

6. Click the Location drop-down list and select a location for the answer. Specifying a location for the answer is an optional step. For details about creating a location, refer to Chapter 3, Configuring Resources.

7. In the CRA Address field enter the interface or circuit address of the CRA.

8. If you want the GSS to perform keepalive checks on the CRA answer, click the Perform KeepAlive Check check box. Uncheck the Perform KeepAlive option if a static one-way delay value is used.

9. If a one way delay time is required, enter a value, in milliseconds, in the One Way Delay field. This value is used by the GSS to calculate a static round-trip time (RTT), with the one-way delay constituting one-half of the round-trip time that is used for all DNS races involving this answer.

10. Click Submit to create your new CRA-type answer. You return to the Answers list page.

Creating a Name Server-Type Answer

A name server (NS) answer type specifies the IP address of a DNS name server to which DNS queries are forwarded from the GSS. Using the name server forwarding feature, queries are forwarded to an external (non-GSS) name server for resolution, with the answer passed back to the GSS name server and from there to the requesting D-proxy. As such, the name server answer type acts as a guaranteed fallback resource—a way to resolve requests that the GSS cannot resolve itself—either because the requested content is unknown to the GSS, or because the resources that typically handle such requests are unavailable.

Note Once an answer is created the Answer type cannot be modified (for example, from name server to VIP).

To configure a Name Server-type answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1).

3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 7-2).

4. In the Type field, click the Name Server option button. The Name Server Answer section appears in the Creating New Answer details page (Figure 7-9).

Figure 7-9 Creating New Answer—Name Server Answer

5. In the Name field, enter a name for the name server-type answer you are creating. Specifying a name for the answer is an optional step.

6. From the Location drop-down list, select a GSS location to which the answer corresponds. Specifying a location for the answer is an optional step. For details about creating a location, refer to Chapter 3, Configuring Resources.

7. In the Name Server Address field, enter the IP address of the name server that the GSS is to forward requests to.

8. If you want the GSS to perform keepalive checks on the specified Name Server, click the Perform KeepAlive Check check box. The GSS queries the specified name server address to determine online status.

9. If you wish to have the GSS query the name server for a specific domain in determining online status, enter the domain name in the KeepAlive Query Domain field.

If no domain is specified, the GSS queries the default query domain. For instructions on configuring the default query domain, see Chapter 6, Configuring KeepAlives.

10. Click Submit to create your new name server-type answer. You return to the Answers list page.

Modifying an Answer

Once you have configured your answers, they can be modified at any time. However, once an answer is created the answer type cannot be modified (for example, from VIP to CRA).

To modify an existing answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears.

3. Click the Modify Answer icon located to the left of the answer you want to modify. The Modifying Answer details page appears (Figure 7-10).

Figure 7-10 Modifying Answer Details Page

4. Use the fields provided to modify the answer configuration.

5. Click Submit to save your configuration changes. You return to the Answers list page.

Suspending an Answer

If you have created an answer but wish to temporarily stop the GSS from using it, use the suspend feature on the primary GSSM GUI to prevent that answer from being used by any of the currently configured DNS rules.

If you have already suspended an answer, use the activate feature to reactivate the answer (see the "Reactivating an Answer" section).

To suspend an answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1).

3. Click the Modify Answer icon located to the left of the answer you want to suspend. The Modifying Answer details page appears (see Figure 7-10).

4. Click the Suspend Answer icon in the upper right corner of the page to suspend an answer.

5. Click OK to confirm your decision to suspend the answer. You return to the Answers list screen. The modified answer has a status of Suspended.

Reactivating an Answer

If you have already suspended an answer, use the activate feature to reactivate the answer.

To reactivate an answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1).

3. Click the Modify Answer icon located to the left of the answer you want to activate. All suspended answers have a status of Suspended in the list. The Modifying Answer details page appears (see Figure 7-10).

4. Click the Activate Answer icon in the upper right corner of the page to reactivate an answer.

5. Click OK to confirm your decision to reactivate the answer. You return to the Answers list screen. The modified answer has a status of Active.

Suspending or Reactivating All Answers in a Location

Answers can be grouped and managed according to an established GSS location. Using a location to manage your answers makes it easier for you to quickly suspend or activate answers in a particular area of your network, for example, shutting down one or more data centers for the purposes of software upgrades or regular maintenance.

The GSS automatically detects and routes requests around suspended answers.

Note Suspending all answers in a location overrides the active or suspended state of an individual answer.

To suspend or reactivate answers based on their location:

1. From the primary GSSM GUI, click the Resources tab.

2. Click the Locations navigation link. The Locations list page appears.

3. Click the Modify Location icon located to the left of the location that includes answers that you want to suspend or reactivate. The Modifying Location details page appears.

4. Perform one of the following:

–To suspend answers associated with this location, click the Suspend All Answers in This Location icon.

–To reactivate suspended answers associated with this location, click the Activate All Answers in This Location icon.

5. Confirm your decision to suspend or activate the answers associated with this location.

6. Click OK. You return to the Locations list page.

Deleting an Answer

If you have created an answer but wish to delete it from the GSS, use the delete feature on the primary GSSM GUI to remove that answer.

Caution Deletions of any kind cannot be undone in the primary GSSM. If you might want to use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to Chapter 9, GSS Administration and Troubleshooting for details.

To delete an answer:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1).

3. Click the Modify Answer icon located to the left of the answer you want to remove. The Modifying Answer details page appears (see Figure 7-10).

4. Click the Delete Answer icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer.

5. Click OK to confirm your decision. You return to the Answers list page.

Configuring and Modifying Answer Groups

Answer groups are lists of GSS resources that are candidates to respond to DNS queries received from a user for a hosted domain. Using the DNS rules feature, these lists of network resources are associated with a particular balance method, which is used to resolve the request.

•In the case of a VIP answer group type, the GSS selects one or more VIPs using the balance method specified in the DNS rule.

•In the case of a CRA answer group type, all CRAs in the answer group are queried and then "race" to respond first to the D-proxy with their IP address.

•In the case of a name server answer group type, the GSS selects a name server using the balance method specified in the DNS rule and forwards the client's request to that name server.

A DNS rule can have up to three balance clauses, each specifying a different answer group from which an answer can be chosen, after taking load threshold, order, and weight factors into account for each answer.

Before creating your answer groups, you must first configure the answers that make up those groups. See the "Configuring and Modifying Answers" section for more information on creating GSS answers.

This section includes the following procedures:

•Creating an Answer Group

•Modifying an Answer Group

•Suspending or Reactivating an Answer Group

•Suspending or Reactivating All Answers in an Answer Group Associated with an Owner

•Deleting an Answer Group

Creating an Answer Group

To create an answer group:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears (Figure 7-11).

Figure 7-11 Answer Group List Page

3. Click the Create Answer Group icon. The Creating New Answer Group details page appears (Figure 7-12).

Figure 7-12 Creating New Answer Group Details Page—General Configuration

4. In the General Configuration details page (General Configuration navigation link), perform the following:

– In the Name field, enter a name for the new answer group. The answer group name cannot contain spaces.

– From the Type drop-down list, choose one of the three options:

• Name Server—The answer group consists of configured name servers

• CRA—The answer group consists of content routing agents (CRAs) for use with the Boomerang Server component of the GSS

•VIP—The answer group consists of virtual IPs controlled by an SLB device such as a CSS or CSM

5. From the Owner drop-down list, select the GSS owner with which the answer group will be associated. For details about creating an owner, refer to Chapter 3, Configuring Resources.

6. In the Comments text area, enter a description or other instructions regarding the new answer group.

7. Click the Add Answers navigation link to access the Add Answers section of the page (Figure 7-13). Perform the following:

a. Click the check box corresponding to each answer you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers and proceed to the next step.

b. Click the Add Selected button. The selected answers are added to the answer group. Answers can belong to more than one answer group simultaneously.

c. Repeat Steps a and b if your answers span multiple pages.

Note If an answer is added to multiple answer groups, when viewing the hit count of answers from either the Answer Status list page or the show statistics dns CLI command output, the number of hits provided represents the aggregate number of hits for that answer across all answer groups.

Figure 7-13 Creating New Answer Group Details Page—Add Answers

8. Click the General Configuration navigation link to return to the General Configuration section. The newly added answers appear in the Current Members section (Figure 7-14). There are different configuration options depending on the type of answer group.

Figure 7-14 Creating New Answer Group Details Page—Current Members

9. Perform one of the following:

Note If you are unsure of the purpose of the order, weight, or load threshold settings, refer to Chapter 1, Introducing the Global Site Selector, the "Balance Methods" section for background information.

– If configuring a Name Server type answer group, assign an order and weight to each Answer in the answer group using the field and drop-down list provided.

– If configuring a VIP type answer group, assign an order, load threshold (LT), and weight to each answer in the answer group using the fields and drop-down lists provided.

Note Load thresholds, which allow the GSS to make routing decisions based on how heavily a particular resource is being tasked, can only be assigned to answers using the KAL-AP keepalive.

– If configuring CRA, no configuration parameters are required.

10. Click the Submit button to save your answer group.

Modifying an Answer Group

Once you have created your answer groups, you can use the primary GSSM GUI to make modifications to their configurations, adding and removing answers, changing the order, weight, and load thresholds of individual answers. Answers can belong to more than one answer group. However, once you have added answers to an answer group, you cannot change the type of an answer group (for example, from VIP to CRA).

To modify an answer group:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 7-11).

3. Click the Modify Answer Group icon located to the left of the answer group you want to modify. The Modify Answer Group details page appears.

4. In the General Configuration details page (General Configuration navigation link), use the fields provided to modify the name, owner, or comments for the answer group.

5. Click the Add Answers navigation link. Click the check box corresponding to each answer you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers, then click Add Selected, before proceeding to another page of answers.

6. To remove answers from the answer group, click the Remove Answers navigation link. The Remove Answers section of the page appears (Figure 7-15). Click the check box accompanying each answer you wish to remove from the list, then click the Remove Selected button. The deleted answers are removed from the page.

Figure 7-15 Modifying Answer Group - Remove Answers

7. Review your updated answer group under the Current Members section of the General Configuration details page (see Figure 7-14).

8. Click the Submit button to save your changes. You return to the Answer Groups Lists page.

Suspending or Reactivating an Answer Group

If you have created an answer group but wish to temporarily stop the GSS from directing requests to it, you can use the suspend answer group feature on the primary GSSM GUI to temporarily suspend the answers that make up that group, preventing that answer group from being used by any of the currently configured DNS rules.

Note Suspending the answers in one answer group also affects any other answer groups to which those answers belong.

If you have already suspended the answers in an answer group, use the activate answers feature to reactivate the answer group.

To suspend or reactivate an answer group:

1. From the primary GSSM GUI, click the DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 7-11).

3. Click the Modify Answer Group icon located to the left of the answer group you want to suspend or reactivate. The Modifying Answer Group details page appears (Figure 7-16).

Figure 7-16 Modifying Answer Group - Suspend Answers Icon

4. To suspend an answer group, click the Suspend Answers button in the upper right corner of the page.

5. If you are reactivating a suspended answer group, click the Activate Answers icon.

6. Click OK to confirm your decision to suspend or reactivate the answers in the answer group. You return to the Answer Groups list page.

7. To view the status of the answers that you suspended or activated, refer to Chapter 10, Monitoring GSS Performance.

Suspending or Reactivating All Answers in an Answer Group Associated with an Owner

Answers that have been added to answer groups can be grouped and managed according to a GSS owner. Using a GSS owner to manage your answer groups makes it easier for you to quickly suspend or activate related answers.

To suspend or reactivate all answers in answer groups associated with a GSS owner:

1. From the primary GSSM GUI, click the Resources tab.

2. Click the Owners navigation link. The Owners list page appears (Figure 7-17).

Figure 7-17 Owners List Page

3. Click the Modify Owner icon located to the left of the answer group you want to suspend or reactivate. The Modifying Owner details page appears (Figure 7-18).

Figure 7-18 Modifying Owners Details Page

4. Perform one of the following:

–To suspend all answers in all answer groups associated with this owner, click the Suspend All Answers in All Groups for This Owner icon in the upper-right corner of the details page.

–To reactivate all suspended answers associated with this owner, click the Activate All Answers in All Groups for This Owner icon in the upper-right corner of the details page.

5. Confirm your decision to suspend or activate the answers. Click OK. You return to the Owner list page.

Deleting an Answer Group

If you have created an answer group and want to delete it from the GSS, use the delete feature on the primary GSSM GUI to remove that answer group. You cannot delete answer groups that are linked to DNS rules. Disassociate your answer group from all DNS rules before attempting to delete it (refer to Chapter 8, Building and Modifying DNS Rules). Deleting an answer group does not delete the answers contained in the answer group.

Caution Deletions of any kind cannot be undone in the primary GSSM. If you might use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to Chapter 9, GSS Administration and Troubleshooting for details.

To delete an answer group:

1. From the primary GSSM GUI, click DNS Rules tab.

2. Click the Answer Groups navigation link. The Answer Groups list page appears.

3. Click the Modify Answer Group icon located to the left of the answer group you want to remove. The Modifying Answer Group details page appears (see Figure 7-16).

4. Click the Delete Answer Group icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer group.

5. Click OK to confirm your decision. You return to the Answer Groups list page.

Where to Go Next

Chapter 8, Building and Modifying DNS Rules, describes constructing the DNS rules that govern all global server load balancing on your GSS network.

	Cisco GSS Configuration Guide (Software Version 1.1)
	Configuring Answers and Answer Groups
Cisco GSS Configuration Guide (Software Version 1.1) Index Preface Introducing the Global Site Selector Setting Up Your GSS Configuring Resources Configuring Source Address Lists Configuring Domain Lists Configuring KeepAlives Configuring Answers and Answer Groups Building and Modifying DNS Rules GSS Administration and Troubleshooting Monitoring GSS Performance Glossary	Download this chapter Configuring Answers and Answer Groups Download the complete book Cisco Global Site Selector Configuration Guide Book-Length PDF, Software Version 1.1 (PDF - 5 MB) Table Of Contents Configuring Answers and Answer Groups Configuring and Modifying Answers Creating a VIP-Type Answer VIP Answer—ICMP KeepAlive VIP Answer—TCP KeepAlive VIP Answer—HTTP HEAD KeepAlive VIP Answer—KAL-AP KeepAlive Creating a CRA-Type Answer Creating a Name Server-Type Answer Modifying an Answer Suspending an Answer Reactivating an Answer Suspending or Reactivating All Answers in a Location Deleting an Answer Configuring and Modifying Answer Groups Creating an Answer Group Modifying an Answer Group Suspending or Reactivating an Answer Group Suspending or Reactivating All Answers in an Answer Group Associated with an Owner Deleting an Answer Group Where to Go Next Configuring Answers and Answer Groups This chapter describes how to create and configure GSS answers and answer groups. It contains the following major sections: •Configuring and Modifying Answers •Configuring and Modifying Answer Groups Configuring and Modifying Answers In a GSS network, the term answers refers to resources that respond to content queries. When you create an answer using the primary GSSM, you are simply identifying a resource on your GSS network to which queries can be directed and that can provide your user's D-proxy with the address of a valid host to serve their request. Examples of GSS answers are: •VIP—Virtual IP (VIP) addresses associated with an SLB such as the Cisco CSS, Cisco CSM, Cisco IOS-compliant SLB, LocalDirector, a Web server, cache, or other geographically dispersed SLBs in a global network deployment. •Name Server—A configured DNS name server on your network that can answer queries that the GSS cannot resolve. •CRA—Content routing agents that use a resolution process called DNS race to send identical and simultaneous responses back to a user's D-proxy. Once created, answers are grouped together as resource pools from which the GSS, using one of a number of available balance methods in a DNS rule, can choose the most appropriate answer for each user request. In addition, once the query is passed to the answer, intelligence on that resource can be applied in choosing the best host. For example, a request that is routed to VIP associated with a CSS is evaluated by the CSS after it is received and directed to the most suitable host managed by that CSS. In addition to specifying a resource, each answer also provides you with the option of specifying a keepalive for that resource a method by which the GSS can periodically check to see if the resource is still up and running. The keepalive monitoring method available to you varies with the resource type, as explained in this section. This section includes the following procedures: •Creating a VIP-Type Answer •Creating a CRA-Type Answer •Creating a Name Server-Type Answer •Modifying an Answer •Suspending an Answer •Reactivating an Answer •Suspending or Reactivating All Answers in a Location •Deleting an Answer Creating a VIP-Type Answer The VIP-type answer refers to a virtual IP address (VIP) associated with an SLB device such as a Cisco CSS or CSM. When the GSS receives requests for content that is managed by an SLB, the GSS returns an A-record containing the VIP of the SLB that manages that content. When configuring a VIP-type answer you have the option of configuring one of a variety of different keepalive types to test for that answer. For a KAL-AP keepalive, it is necessary to configure shared keepalives before configuring your answer. Refer to Chapter 6, Configuring KeepAlives for more information on creating shared keepalives. Note Once an answer is created the Answer type cannot be modified (for example, from VIP to CRA). To configure a VIP-type answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (Figure 7-1). Figure 7-1 Answers List Page 3. Click the Create Answer icon. The Creating New Answer detail page appears (Figure 7-2). Figure 7-2 Creating New Answer Details Page 4. In the Type field, click the VIP option button. The VIP Answer section appears in the details page (Figure 7-3). Figure 7-3 Creating New Answer—VIP Details Page 5. In the Name field, enter a name for the VIP-type answer you are creating. Specifying a name for the answer is an optional step. 6. From the Location drop-down list, select an GSS location to which the answer corresponds. Specifying a location for an answer is an optional step. For details about creating a location, refer to Chapter 3, Configuring Resources. 7. In the VIP address field, enter the VIP address to which the GSS will forward requests. 8. Choose from one of the five keepalive types for your VIP answer: – None—Does not send keepalive queries to the VIP. The GSS assumes that the VIP is always alive. – ICMP—Sends an ICMP echo message (ping) to the specified address. Online status is determined by the response received from the device, indicating simple connectivity to the network. – TCP—Sends a TCP handshake to the specified IP address and port number of the remote device to determine service viability (three-way handshake and connection termination method), returning the online status of the device. – HTTP-Head—Sends a TCP format HTTP HEAD request to an origin web server at a specified address. Online status of the device is determined in the form of an HTTP Response Status Code of 200 (for example, HTTP/1.0 200 OK) from the server as well as information on the web page status and content size. – KAL-AP—Sends a detailed query to the Cisco CSS or CSM to extract load and availability. Online status is determined when these SLBs respond with information about a hosted domain name, host VIP address, or a configured tag on a content rule. The following procedures describe how to configure the properties for the individual VIP keepalives. The default values used for each of the VIP keepalives are determined by the values specified in the Global Keepalive Properties details page. –VIP Answer—ICMP KeepAlive –VIP Answer—TCP KeepAlive –VIP Answer—HTTP HEAD KeepAlive –VIP Answer—KAL-AP KeepAlive VIP Answer—ICMP KeepAlive To define the ICMP keepalive for your VIP answer, see Figure 7-4 and perform the following steps: Figure 7-4 Answer Details Page—ICMP KeepAlive VIP Answer 1. The VIP Address check box is automatically checked to instruct the GSS to send an ICMP echo message (ping) to the VIP address of the remote device and determine online status. If necessary, uncheck the VIP Address check box and select an ICMP-type shared keepalive from the Shared ICMP Keepalive drop-down list. 2. If the ICMP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section: –In the Number of Retries field, specify the number of times the GSS retransmits an ICMP echo request packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The range is 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value. –In the Number of Successful Probes field, specify the number of consecutive successful ICMP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The range is 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value. Note For background details on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section. 3. Click the Submit button to save your ICMP keepalive VIP answer. You return to the Answers list page. VIP Answer—TCP KeepAlive To define the TCP shared keepalive for your VIP answer, see Figure 7-5 and perform the following steps: Figure 7-5 Answer Details Page—TCP KeepAlive VIP Answer 1. The VIP Address check box is automatically checked to instruct the GSS to send a TCP keepalive to the VIP address of the remote device and determine online status. If necessary, uncheck the VIP Address check box and choose a TCP-type shared keepalive from the Shared TCP Keepalive drop-down list. 2. In the Destination Port field enter the port on the remote device that is to receive the TCP keepalive request. The port range is 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value. 3. If you enabled the VIP Address check box, specify the TCP keepalive connection termination method: – Default—Always use the globally defined TCP keepalive connection method. –Reset—The GSS immediately terminates the TCP connection by using a hard reset. –Graceful—The GSS initiates the graceful closing of a TCP connection by using the standard three-way connection termination method. 4. If the TCP global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section: –In the Number of Retries field, specify the number of times the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The range is 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value. Note When using the Graceful termination sequence, there are two packets that require acknowledgement: SYN and FIN. –In the Number of Successful Probes field, specify the number of consecutive successful TCP keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The range is 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value. Note For background details on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section. 5. Click the Submit button to save your TCP keepalive VIP answer. You return to the Answers list page. VIP Answer—HTTP HEAD KeepAlive To define the HTTP HEAD shared keepalive for your VIP answer, see Figure 7-6 and perform the following steps: Figure 7-6 Answer Details Page—HTTP HEAD KeepAlive VIP Answer 1. The VIP Address check box is automatically checked to instruct the GSS to send a TCP format HTTP HEAD request to the web server at an address you specified and determine online status. If necessary, uncheck the VIP Address check box and select an HTTP-type shared keepalive from the Shared HTTP HEAD keepalive drop-down list. 2. In the Destination Port field enter the port on the remote device that receives the HTTP HEAD-type keepalive request from the GSS. The port range is 1 to 65535. If you do not specify a destination port, the GSS uses the globally configured value. 3. In the Host Tag field, enter an optional domain name that is sent to the VIP as part of the HTTP HEAD query in the Host tag field. This tag allows an SLB to resolve the keepalive request to a particular website even when multiple sites are represented by the same VIP. 4. In the Path field, enter the path that is relative to the server website being queried in the HTTP HEAD request. If you do not specify a default path, the GSS uses the globally configured value. For example: `/company/owner` 5. If you enabled the VIP Address check box, specify the HTTP HEAD keepalive connection termination method: – Default—Always use the globally defined HTTP HEAD keepalive connection method. –Reset—The GSS immediately terminates the TCP formatted HTTP HEAD connection by using a hard reset. –Graceful—The GSS initiates the graceful closing of a TCP formatted HTTP HEAD connection by using the standard three-way connection termination method. 6. If the HTTP HEAD global keepalive configuration is set to the Fast KAL Type and the VIP Address is checked, specify the following parameters in the Fast Keepalive Settings section: –In the Number of Retries field, specify the number of times the GSS retransmits a TCP packet before declaring the device offline. As you adjust the Number of Retries parameter, you change the detection time determined by the GSS. By increasing the number of retries you increase the detection time. Reducing the number of retries has the reverse effect. The range is 1 to 10 retries. If you do not specify a value, the GSS uses the globally configured value. Note When using the Graceful termination sequence, there are three packets that require acknowledgement: SYN, HEAD, and FIN. –In the Number of Successful Probes field, specify the number of consecutive successful HTTP HEAD keepalive attempts (probes) that must be recognized by the GSS before bringing an answer back online (and reintroducing it back into the GSS network). The range is 1 to 5 probes. If you do not specify a value, the GSS uses the globally configured value. Note For background details on keepalive detection time, refer to Chapter 1, Introducing the Global Site Selector, the "Keepalives" section. 7. Click the Submit button to save your HTTP HEAD keepalive VIP answer. You return to the Answers list page. VIP Answer—KAL-AP KeepAlive To define the KAL-AP shared keepalive for your VIP answer, see Figure 7-7 and perform the following steps: Figure 7-7 Answer Details Page—KAL-AP Keepalive VIP Answer 1. From the KAL-AP Type drop-down list, select the format of the KAL-AP keepalive query. Your choices are: – KAL-AP By Tag—Embeds an alphanumeric tag associated with the VIP in the KAL-AP request. The tag value is used to match the correct shared keepalive VIP, thus avoiding confusion that can be caused when probing for the status of a VIP that is located behind a firewall network address translation (NAT). – KAL-AP By VIP—Embeds the keepalive VIP address in the KAL-AP request. The KAL-AP queries the keepalive address to determine online status. 2. If you chose KAL-AP By VIP, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list. 3. If you chose KAL-AP By Tag, select the appropriate KAL-AP type keepalive from the Shared KAL-AP Keepalive drop-down list, then enter a unique alphanumeric value in the Tag field. This is used as a "key" by the CSS or GSSM that matches the KAL-AP request with the appropriate VIP. 4. Click the Submit button to save your KAL-AP keepalive VIP answer. You return to the Answers list page. Creating a CRA-Type Answer The content routing agent (CRA) answer type relies on content routing agents and the GSS to choose a suitable answer for a given query based on the proximity of two or more possible hosts to the requesting D-proxy. With the CRA answer type, requests received from a particular D-proxy are served by the content server that responds first to the request. Response time is measured using a DNS race, coordinated by the GSS and content routing agents running on each content server. In the race, multiple hosts respond simultaneously to a request. The server with the fastest response time (the shortest network delay between itself and the client's D-proxy) is chosen to serve the content. The CRA answer type is designed to work with the GSS when the boomerang balance method is selected for a DNS rule (utilizing the Boomerang Server component of the GSS). Closeness is determined when multiple hosts reply to the requesting D-proxy simultaneously in what is referred to as a "DNS race." The GSS coordinates the start of the race so that all CRAs initiate their response at the same time. The first DNS reply to reach the D-proxy is chosen by the name server as the host containing the answer. Note Once an answer is created the Answer type cannot be modified (for example, from CRA to VIP). To configure a CRA-type answer type: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1). 3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 7-2). 4. In the Type selection field, click the CRA option button. The CRA Answer section appears in the details page (Figure 7-8). Figure 7-8 Creating New Answer—CRA Answer 5. In the Name field enter a name for the CRA-type answer being created. Specifying a name for the answer is an optional step. 6. Click the Location drop-down list and select a location for the answer. Specifying a location for the answer is an optional step. For details about creating a location, refer to Chapter 3, Configuring Resources. 7. In the CRA Address field enter the interface or circuit address of the CRA. 8. If you want the GSS to perform keepalive checks on the CRA answer, click the Perform KeepAlive Check check box. Uncheck the Perform KeepAlive option if a static one-way delay value is used. 9. If a one way delay time is required, enter a value, in milliseconds, in the One Way Delay field. This value is used by the GSS to calculate a static round-trip time (RTT), with the one-way delay constituting one-half of the round-trip time that is used for all DNS races involving this answer. 10. Click Submit to create your new CRA-type answer. You return to the Answers list page. Creating a Name Server-Type Answer A name server (NS) answer type specifies the IP address of a DNS name server to which DNS queries are forwarded from the GSS. Using the name server forwarding feature, queries are forwarded to an external (non-GSS) name server for resolution, with the answer passed back to the GSS name server and from there to the requesting D-proxy. As such, the name server answer type acts as a guaranteed fallback resource—a way to resolve requests that the GSS cannot resolve itself—either because the requested content is unknown to the GSS, or because the resources that typically handle such requests are unavailable. Note Once an answer is created the Answer type cannot be modified (for example, from name server to VIP). To configure a Name Server-type answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1). 3. Click the Create Answer icon. The Creating New Answer details page appears (see Figure 7-2). 4. In the Type field, click the Name Server option button. The Name Server Answer section appears in the Creating New Answer details page (Figure 7-9). Figure 7-9 Creating New Answer—Name Server Answer 5. In the Name field, enter a name for the name server-type answer you are creating. Specifying a name for the answer is an optional step. 6. From the Location drop-down list, select a GSS location to which the answer corresponds. Specifying a location for the answer is an optional step. For details about creating a location, refer to Chapter 3, Configuring Resources. 7. In the Name Server Address field, enter the IP address of the name server that the GSS is to forward requests to. 8. If you want the GSS to perform keepalive checks on the specified Name Server, click the Perform KeepAlive Check check box. The GSS queries the specified name server address to determine online status. 9. If you wish to have the GSS query the name server for a specific domain in determining online status, enter the domain name in the KeepAlive Query Domain field. If no domain is specified, the GSS queries the default query domain. For instructions on configuring the default query domain, see Chapter 6, Configuring KeepAlives. 10. Click Submit to create your new name server-type answer. You return to the Answers list page. Modifying an Answer Once you have configured your answers, they can be modified at any time. However, once an answer is created the answer type cannot be modified (for example, from VIP to CRA). To modify an existing answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears. 3. Click the Modify Answer icon located to the left of the answer you want to modify. The Modifying Answer details page appears (Figure 7-10). Figure 7-10 Modifying Answer Details Page 4. Use the fields provided to modify the answer configuration. 5. Click Submit to save your configuration changes. You return to the Answers list page. Suspending an Answer If you have created an answer but wish to temporarily stop the GSS from using it, use the suspend feature on the primary GSSM GUI to prevent that answer from being used by any of the currently configured DNS rules. If you have already suspended an answer, use the activate feature to reactivate the answer (see the "Reactivating an Answer" section). To suspend an answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1). 3. Click the Modify Answer icon located to the left of the answer you want to suspend. The Modifying Answer details page appears (see Figure 7-10). 4. Click the Suspend Answer icon in the upper right corner of the page to suspend an answer. 5. Click OK to confirm your decision to suspend the answer. You return to the Answers list screen. The modified answer has a status of `Suspended`. Reactivating an Answer If you have already suspended an answer, use the activate feature to reactivate the answer. To reactivate an answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1). 3. Click the Modify Answer icon located to the left of the answer you want to activate. All suspended answers have a status of `Suspended` in the list. The Modifying Answer details page appears (see Figure 7-10). 4. Click the Activate Answer icon in the upper right corner of the page to reactivate an answer. 5. Click OK to confirm your decision to reactivate the answer. You return to the Answers list screen. The modified answer has a status of `Active`. Suspending or Reactivating All Answers in a Location Answers can be grouped and managed according to an established GSS location. Using a location to manage your answers makes it easier for you to quickly suspend or activate answers in a particular area of your network, for example, shutting down one or more data centers for the purposes of software upgrades or regular maintenance. The GSS automatically detects and routes requests around suspended answers. Note Suspending all answers in a location overrides the active or suspended state of an individual answer. To suspend or reactivate answers based on their location: 1. From the primary GSSM GUI, click the Resources tab. 2. Click the Locations navigation link. The Locations list page appears. 3. Click the Modify Location icon located to the left of the location that includes answers that you want to suspend or reactivate. The Modifying Location details page appears. 4. Perform one of the following: –To suspend answers associated with this location, click the Suspend All Answers in This Location icon. –To reactivate suspended answers associated with this location, click the Activate All Answers in This Location icon. 5. Confirm your decision to suspend or activate the answers associated with this location. 6. Click OK. You return to the Locations list page. Deleting an Answer If you have created an answer but wish to delete it from the GSS, use the delete feature on the primary GSSM GUI to remove that answer. Caution Deletions of any kind cannot be undone in the primary GSSM. If you might want to use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to Chapter 9, GSS Administration and Troubleshooting for details. To delete an answer: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answers navigation link. The Answers list page appears (see Figure 7-1). 3. Click the Modify Answer icon located to the left of the answer you want to remove. The Modifying Answer details page appears (see Figure 7-10). 4. Click the Delete Answer icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer. 5. Click OK to confirm your decision. You return to the Answers list page. Configuring and Modifying Answer Groups Answer groups are lists of GSS resources that are candidates to respond to DNS queries received from a user for a hosted domain. Using the DNS rules feature, these lists of network resources are associated with a particular balance method, which is used to resolve the request. •In the case of a VIP answer group type, the GSS selects one or more VIPs using the balance method specified in the DNS rule. •In the case of a CRA answer group type, all CRAs in the answer group are queried and then "race" to respond first to the D-proxy with their IP address. •In the case of a name server answer group type, the GSS selects a name server using the balance method specified in the DNS rule and forwards the client's request to that name server. A DNS rule can have up to three balance clauses, each specifying a different answer group from which an answer can be chosen, after taking load threshold, order, and weight factors into account for each answer. Before creating your answer groups, you must first configure the answers that make up those groups. See the "Configuring and Modifying Answers" section for more information on creating GSS answers. This section includes the following procedures: •Creating an Answer Group •Modifying an Answer Group •Suspending or Reactivating an Answer Group •Suspending or Reactivating All Answers in an Answer Group Associated with an Owner •Deleting an Answer Group Creating an Answer Group To create an answer group: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears (Figure 7-11). Figure 7-11 Answer Group List Page 3. Click the Create Answer Group icon. The Creating New Answer Group details page appears (Figure 7-12). Figure 7-12 Creating New Answer Group Details Page—General Configuration 4. In the General Configuration details page (General Configuration navigation link), perform the following: – In the Name field, enter a name for the new answer group. The answer group name cannot contain spaces. – From the Type drop-down list, choose one of the three options: • Name Server—The answer group consists of configured name servers • CRA—The answer group consists of content routing agents (CRAs) for use with the Boomerang Server component of the GSS •VIP—The answer group consists of virtual IPs controlled by an SLB device such as a CSS or CSM 5. From the Owner drop-down list, select the GSS owner with which the answer group will be associated. For details about creating an owner, refer to Chapter 3, Configuring Resources. 6. In the Comments text area, enter a description or other instructions regarding the new answer group. 7. Click the Add Answers navigation link to access the Add Answers section of the page (Figure 7-13). Perform the following: a. Click the check box corresponding to each answer you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers and proceed to the next step. b. Click the Add Selected button. The selected answers are added to the answer group. Answers can belong to more than one answer group simultaneously. c. Repeat Steps a and b if your answers span multiple pages. Note If an answer is added to multiple answer groups, when viewing the hit count of answers from either the Answer Status list page or the show statistics dns CLI command output, the number of hits provided represents the aggregate number of hits for that answer across all answer groups. Figure 7-13 Creating New Answer Group Details Page—Add Answers 8. Click the General Configuration navigation link to return to the General Configuration section. The newly added answers appear in the Current Members section (Figure 7-14). There are different configuration options depending on the type of answer group. Figure 7-14 Creating New Answer Group Details Page—Current Members 9. Perform one of the following: Note If you are unsure of the purpose of the order, weight, or load threshold settings, refer to Chapter 1, Introducing the Global Site Selector, the "Balance Methods" section for background information. – If configuring a Name Server type answer group, assign an order and weight to each Answer in the answer group using the field and drop-down list provided. – If configuring a VIP type answer group, assign an order, load threshold (LT), and weight to each answer in the answer group using the fields and drop-down lists provided. Note Load thresholds, which allow the GSS to make routing decisions based on how heavily a particular resource is being tasked, can only be assigned to answers using the KAL-AP keepalive. – If configuring CRA, no configuration parameters are required. 10. Click the Submit button to save your answer group. Modifying an Answer Group Once you have created your answer groups, you can use the primary GSSM GUI to make modifications to their configurations, adding and removing answers, changing the order, weight, and load thresholds of individual answers. Answers can belong to more than one answer group. However, once you have added answers to an answer group, you cannot change the type of an answer group (for example, from VIP to CRA). To modify an answer group: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 7-11). 3. Click the Modify Answer Group icon located to the left of the answer group you want to modify. The Modify Answer Group details page appears. 4. In the General Configuration details page (General Configuration navigation link), use the fields provided to modify the name, owner, or comments for the answer group. 5. Click the Add Answers navigation link. Click the check box corresponding to each answer you wish to add to the answer group. If the list of answers on your GSS network spans more than one page, select the answers from only the first page of answers, then click Add Selected, before proceeding to another page of answers. 6. To remove answers from the answer group, click the Remove Answers navigation link. The Remove Answers section of the page appears (Figure 7-15). Click the check box accompanying each answer you wish to remove from the list, then click the Remove Selected button. The deleted answers are removed from the page. Figure 7-15 Modifying Answer Group - Remove Answers 7. Review your updated answer group under the Current Members section of the General Configuration details page (see Figure 7-14). 8. Click the Submit button to save your changes. You return to the Answer Groups Lists page. Suspending or Reactivating an Answer Group If you have created an answer group but wish to temporarily stop the GSS from directing requests to it, you can use the suspend answer group feature on the primary GSSM GUI to temporarily suspend the answers that make up that group, preventing that answer group from being used by any of the currently configured DNS rules. Note Suspending the answers in one answer group also affects any other answer groups to which those answers belong. If you have already suspended the answers in an answer group, use the activate answers feature to reactivate the answer group. To suspend or reactivate an answer group: 1. From the primary GSSM GUI, click the DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears (see Figure 7-11). 3. Click the Modify Answer Group icon located to the left of the answer group you want to suspend or reactivate. The Modifying Answer Group details page appears (Figure 7-16). Figure 7-16 Modifying Answer Group - Suspend Answers Icon 4. To suspend an answer group, click the Suspend Answers button in the upper right corner of the page. 5. If you are reactivating a suspended answer group, click the Activate Answers icon. 6. Click OK to confirm your decision to suspend or reactivate the answers in the answer group. You return to the Answer Groups list page. 7. To view the status of the answers that you suspended or activated, refer to Chapter 10, Monitoring GSS Performance. Suspending or Reactivating All Answers in an Answer Group Associated with an Owner Answers that have been added to answer groups can be grouped and managed according to a GSS owner. Using a GSS owner to manage your answer groups makes it easier for you to quickly suspend or activate related answers. To suspend or reactivate all answers in answer groups associated with a GSS owner: 1. From the primary GSSM GUI, click the Resources tab. 2. Click the Owners navigation link. The Owners list page appears (Figure 7-17). Figure 7-17 Owners List Page 3. Click the Modify Owner icon located to the left of the answer group you want to suspend or reactivate. The Modifying Owner details page appears (Figure 7-18). Figure 7-18 Modifying Owners Details Page 4. Perform one of the following: –To suspend all answers in all answer groups associated with this owner, click the Suspend All Answers in All Groups for This Owner icon in the upper-right corner of the details page. –To reactivate all suspended answers associated with this owner, click the Activate All Answers in All Groups for This Owner icon in the upper-right corner of the details page. 5. Confirm your decision to suspend or activate the answers. Click OK. You return to the Owner list page. Deleting an Answer Group If you have created an answer group and want to delete it from the GSS, use the delete feature on the primary GSSM GUI to remove that answer group. You cannot delete answer groups that are linked to DNS rules. Disassociate your answer group from all DNS rules before attempting to delete it (refer to Chapter 8, Building and Modifying DNS Rules). Deleting an answer group does not delete the answers contained in the answer group. Caution Deletions of any kind cannot be undone in the primary GSSM. If you might use the deleted data at a later point in time, we recommend performing a database backup of your GSSM. Refer to Chapter 9, GSS Administration and Troubleshooting for details. To delete an answer group: 1. From the primary GSSM GUI, click DNS Rules tab. 2. Click the Answer Groups navigation link. The Answer Groups list page appears. 3. Click the Modify Answer Group icon located to the left of the answer group you want to remove. The Modifying Answer Group details page appears (see Figure 7-16). 4. Click the Delete Answer Group icon in the upper right corner of the page. The GSS software prompts you to confirm your decision to delete the answer group. 5. Click OK to confirm your decision. You return to the Answer Groups list page. Where to Go Next Chapter 8, Building and Modifying DNS Rules, describes constructing the DNS rules that govern all global server load balancing on your GSS network.
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