Force TTL on a Caching Name Server

Mark Andrews Mark_Andrews at
Thu Sep 7 21:31:32 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 
> reconsider.
>                            - Kevin

	And any competent C programer should be able to add the two
	or so lines it would take to cap the ttl in responses w/o
	having to effectively kill the cache.

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