By default the CAS server will only resolve server names. At the beginning this will take longer as there are a lot of new servers. There is an option to resolve client names as well but this is disabled by default. I would have to double check if there is an option to limit the ranges.
If you want you can also specify a host name file to manually map IP addresses to server names. You can do this by updating the following file
<install drive>:\Program Files\Compuware\CAS\config\dns_map-hcbs.properties
You can also force this to override DNS entries.
The Control for DNS resolution is located in atscon by selecting Advanced Properties Editor
How taxing is it for the CAS to use this file for server name lookups? Our DNS lookups seem to be inconsistent so I'd like to just dump our DNS list into this file. But, if we have 50,000+ entries, would this be more work for the CAS to parse than attempting the DNS lookup?
And, if a server name is in the cache, will the CAS still attempt to look up the name from this file? I know that it won't lookup in DNS, again, if it already has the name. Same behavior with this file?
Slightly related but it's a best practise to limit the number of servers by using "Accepted server IP address range" in /Diagconsole.
By specifying for example the IP ranges in your DC(s), you weed out a lot of noise that eats up capacity and time in the CAS.
And @Brett Barrett , as Alasdair says, the default is to only resolve the servers.
Do you have 50.000 servers?
We figured since we had a huge backlog on unresolved clients (over 200.000, our client cache is 269.000) and plenty resources available on the server we changed DNS_THREADS so we could get rid of the queue. We then monitored it and surely enough after a day the queue almost gone. Problem was when queue was done is went back up to over 200.000, once Again we monitored it and when done wooop back to over 200.000 Again, ideas why its doing this?