Clearing the cache of DNS resolver service - User Guide

You can clear the cache of DNS resolver services deployed to service points within a site.

If you modify the forwarders of an existing namespace, the cached answer to a query might differ from what the newly configured forwarder would return. BlueCat recommends clearing the cache of the site once a forwarder has been modified to ensure that the DNS resolver service uses the answer from the updated forwarder.

On the Sites page, select the site you want to work with.
At the bottom of the site details page, click Clear cache.
Under Clear cache, select one of the following options:
- Clear all cache—clears the cache of all domains within a site.
- Clear cache on specific domains—clears the cache of specified domains within a site. If selected, the following field appears:
  - Domains to clear in cache—enter a list of domains that you would like to clear from the cache, such as www.bluecatnetworks.com.
Click Update.

Behavior when clearing the cache

When clearing the cache of a site:
- For user-defined namespaces, the cache is only cleared based on the query itself and not the records in the answer.
  For example, if you clear the cache for *.bluecatnetworks.com, it would clear the cache for the following types of entries:
```
website.bluecatnetworks.com IN A 1.2.3.4
```
  or
```
www.bluecatnetworks.com IN CNAME website.bluecatnetworks.com
website.bluecatnetworks.com IN A 1.2.3.4
```
  However, the following entry would not be cleared:
```
www.example.com IN CNAME website.bluecatnetworks.com
website.bluecatnetworks.com IN A 1.2.3.4
```
- For discovered and recursive namespaces, if a domain was resolved using a forwarder, the cache for the record would be cleared based on the query itself and the record in the answer.
  For example, if you clear the cache for *.bluecatnetworks.com, it would clear the cache for the following types of entries:
```
website.bluecatnetworks.com IN A 1.2.3.4
```
  or
```
www.bluecatnetworks.com IN CNAME website.bluecatnetworks.com
website.bluecatnetworks.com IN A 1.2.3.4
```
  or
```
www.example.com IN CNAME website.bluecatnetworks.com
website.bluecatnetworks.com IN A 1.2.3.4
```
  Attention: In this example, only the record website.bluecatnetworks.com IN A 1.2.3.4 is cleared. The whole entry is not cleared.
  If you clear the cache for *.example.com, you might still received a cached response for the website.bluecatnetworks.com A record, depending on the TTL of the cached response and whether the query occurred before the TTL of the entry lapsed. To ensure that the cache has been completely cleared, you must also clear the cache for *.bluecatnetworks.com, website.bluecatnetworks.com, and *.com.
When clearing the cache of a site where you specify a domain, a wildcard character is required to clear all subdomains of the specified domain
For example, if you clear the cache for bluecatnetworks.com, only the cache is cleared for bluecatnetworks.com and not www.bluecatnetworks.com.

To ensure that all subdomains are cleared, you must use *.bluecatnetworks.com to ensure that www.bluecatnetworks.com is also cleared.

Clearing the cache of DNS resolver service - User Guide - BlueCat Edge

BlueCat Edge User Guide