Force TTL on a Caching Name Server

Kevin Darcy kcd at
Thu Sep 7 18:55:06 UTC 2006

howting at wrote:
> I got it working by adding the following 2 lines to the options block:
> max-cache-ttl 300;
> max-ncache-ttl 300;
> After restarting named, dig shows that all TTL are capped at 300 :)
> This is the perfect solution I wanted. Thanks for all the help!
Hmm... OK. So if one of your users really likes Hemis (TM) and hits frequently during the course of a day, you 
think it's "perfect" for your nameserver to be querying mine 12 times as 
often as it should be expected to (the TTL I've set on the RRset is 1 
hour, but you're capping it at 5 minutes)? That's an interesting 
definition of "perfect". It's certainly not "perfect" from the 
perspective of my traffic load, my capacity planning for the future, my 
budget, etc.

The DNS infrastructure of the Internet is held together in large part 
through mutual consent and co-operation. Practices such as you are 
describing undermine those, inasmuch as you are putting a burden on 
others for your own selfish reasons. I would seriously urge you to 

                           - Kevin

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