SonicOS 7.1 DNS Guide

DNS Cache

In DNS Proxy, a DNS cache memory saves the most commonly used domains and host addresses, and when it receives the DNS query that match the domain in DNS cache, the firewall directly responds to clients by using the cache records, without processing DNS query and reply proxy.

There are two kinds of DNS Cache:

Static Manually configured by you.
Dynamic Auto-learned by the GMS. For each DNS Query, the SonicOS DNS Proxy does the deep inspection on the URI and records the valid response to the caches.

When a DNS query matches an existing cache entry, the SonicOS DNS Proxy responds directly with the cached URI. This usually decreases the network traffic and, therefore, improves overall network performance.

Static DNS Cache Size

Static DNS cache entry size is always 256 regardless of platform. The static DNS cache is never be deleted unless it is done manually.

Dynamic DNS Cache Size

Dynamic DNS cache size depends on the platform. Some examples are shown here:

Platform Maximum Cache Size
SM 9400
SM 9600
4096
SM 9200 2048
NSA 4600
NSA 5600
NSA 6600
2048
NSA 2600
NSA 3600
1024
TZ600 512

TZ300/TZ300W
TZ400/TZ400W
TZ500/TZ500W

512

If the maximum DNS cache size has been reached when the network security appliance attempts to add an entry to it, the network security appliance will:

  1. Delete the DNS cache entry with the earliest expire time.
  2. Add the new DNS cache entry.

Was This Article Helpful?

Help us to improve our support portal

Techdocs Article Helpful form

  • Hidden
  • Hidden

Techdocs Article NOT Helpful form

  • Still can't find what you're looking for? Try our knowledge base or ask our community for more help.
  • Hidden
  • Hidden