Host Mapping

Host name/IP address mappings are stored in the Host Mapping Table (DNS cache).

This cache can contain the following type of entries:

  • Static Entries—These are mapping pairs that manually added to the cache. There can be up to 64 static entries.

  • Dynamic Entries—Are mapping pairs that are either added by the system as a result of being used by the user, or an entry for each IP address configured on the device by DHCP. There can be 256 dynamic entries.

Name resolution always begins by checking static entries, continues by checking the dynamic entries, and ends by sending requests to the external DNS server. Eight IP addresses are supported per DNS server per host name.

To add a host name and its IP address, complete the following:

Procedure

Step 1

Click General IP Configuration > DNS > Host Mapping.

Step 2

If required, select one of the following options from Clear Table to clear some or all of the entries in the Host Mapping Table.

  • Static Only—Deletes the static hosts.

  • Dynamic Only—Deletes the dynamic hosts.

  • All Dynamic & Static—Deletes the static and dynamic hosts.

The Host Mapping Table displays the following fields:

  • Host Name—User-defined host name or fully-qualified name.

  • IP Address—The host IP address.

  • IP Version—IP version of the host IP address.

  • Type—Is this a Dynamic or Static entry to the cache.

  • Status— Displays the results of attempts to access the host

    • OK—Attempt succeeded.

    • Negative Cache—Attempt failed, do not try again.

    • No Response—There was no response, but system can try again in future.

  • TTL (Sec)— If this is a dynamic entry, how long will it remain in the cache.

  • Remaining TTL (Sec)— If this is a dynamic entry, how much longer will it remain in the cache.

Step 3

To add a host mapping, click Add and configure the following:

  • IP Version—Select Version 6 for IPv6 or Version 4 for IPv4.

  • IPv6 Address Type—Select the IPv6 address type (if IPv6 is used). The options are:

    • Link Local—The IPv6 address uniquely identifies hosts on a single network link. A link local address has a prefix of FE80, isn’t routable, and can be used for communication only on the local network. Only one link local address is supported. If a link local address exists on the interface, this entry replaces the address in the configuration.

    • Global—The IPv6 address is a global Unicast IPV6 type that is visible and reachable from other networks.

  • Link Local Interface—If the IPv6 address type is Link Local, select the interface through which it’s received.

  • Host Name—Enter a user-defined host name or fully qualified name. Host names are restricted to the ASCII letters A through Z (case-insensitive), the digits 0–9, the underscore, and the hyphen. A period (.) is used to separate labels.

  • IP Address—Enter a single address or up to eight associated IP addresses (IPv4 or IPv6).

Step 4

Click Apply. The settings are saved to the Running Configuration file.