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Adding DNS Cache to GTMs

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This example we are adding cache to our internal GTMs that are the first DNS servers configured on most servers so if we could get rid of alot of the noise coming to the Infoblox servers it would be nice.

DNS cache settings are set with optimum values considering the cpu & memory resources available.

None of these settings settings are propagated to other GTMs in sync group.

DNS cache is something very local to the box ( configuration and maintenance ).

 

Here are the instructions we run on each of our four internal GTMs

Implementation:-
1.Create DNS cache as per below.
DNS -> Caches -> click create
Name:- non-wideip-resolver-cache
Keep all default values.
click Finished.

non-transparent-cache.png

Note:- Modifying cache size by default clears the cache of the respective field changed.

 

2.Apply cache created to the DNS profile which will eventually apply to the DNS listeners
DNS  ››  Delivery : Profiles : DNS  ››  Properties : internal_dns
DNS cache -> Enabled.
DNA cache name:- non-wideip-resolver-cache
Click Update

Backout:-
1.Remove cache from the DNS profile which will eventually apply to the DNS listeners
DNS  ››  Delivery : Profiles : DNS  ››  Properties : internal_dns
DNS cache -> Disabled.
Click Update

2.Delete DNS cache as per below.
DNS -> Caches -> select cache name as per below.
Name:- non-wideip-resolver-cache
click Delete.

Test plan:-
1.Please perform 100 digs and make sure it is server from the cache based of splunk logs.

dig @10.11.12.234 www.int.mywiseguys.com

2.Observe cache hits count increasing.

tmsh show ltm dns cache resolver 

3. Run the following command on each iGTM that will show Clientside queries and responses

tmsh show ltm dns

View resouce record cache size (its pretty large so you may want to round to first 1000 records)

tmsh show ltm dns cache records rrset cache non-wideip-transparent-cache

View resource record cache size count

tmsh show ltm dns cache records rrset cache non-wideip-transparent-cache count-only

Clear/Delete cache

synatx: 

tmsh delete <cache-type> type <record-type> cache <cache-name>

example to delete the a records from the resource record cache of the resolver cache named non-wideip-transparent-cache:

tmsh delete rrset type a cache non-wideip-transparent-cache

 

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