Cisco Prime Network Registrar makes the following recommendations on maximum Caching DNS System configuration sizes. A redundant DNS architecture will contain multiple servers, therefore the capacity can be expanded horizontally by adding on new servers. Although Cisco Prime Network Registrar does not put hard limits on many of its configuration objects, these recommended maximums are to ensure a properly functioning DNS deployment.

• Maximum of 100 DNS Views

• Maximum of 500 Exceptions and Forwarders

• Maximum of 3 DNS RPZ Firewall Objects. Note that the RPZ zones can have many thousands of entries.

• Maximum of 12 DNS Firewall Objects (non-RPZ) with no more than 200 domains each

• Maximum of 30 DNS64 Objects

Note

To account for situations where one or more servers are unavailable due to maintenance or outage, it is recommended to include excess capacity in the deployment architecture to accommodate the additional load that must be borne by the remaining live systems. The excess capacity to be deployed or the number of backup systems, will depend on the level of redundancy that you want to achieve. A minimum of n+1 redundancy is recommended.

A Cisco Prime Network Registrar Caching DNS deployment can be categorized as small, medium, or large depending on the number of servers and query load. The following sections are an indication of how to provision the Caching DNS server based on the deployment size.

Note	To ensure a properly functioning DNS system, it is important to monitor system disk space and memory.

The following is a list of common system components and Cisco Prime Network Registrar configurations that may have an impact on performance:

• Firewalls and Connection Tracking may have a negative impact on performance especially in medium to large deployments where the firewall may drop a significant amount of DNS traffic.

• Excessive logging—Either enabling too many log settings, packet logging, or debug logging can decrease server performance.

• IPv6 only networks configured to also use IPv4. IPv6 networks should be configured in IPv6 only mode in order to prevent the server wasting cycles on failed IPv4 communication.