[dns-operations] Who Ignores TTLs ?

Warren Kumari warren at kumari.net
Thu Feb 17 15:59:24 UTC 2011

On Feb 16, 2011, at 9:01 PM, Simon Lyall wrote:

> I keep seeing a persistent complaint that some DNS caching operators  
> ignore TTLs or otherwise keep records for longer than the TTL would  
> indicate.
> I suspect this might be an urban legend since most DNS caching  
> software doesn't even offer this as an option last time I checked.

I suspect that the genesis of this belief is from an Online provider  
in America.

They used to ignore all TTLs and overwrite them with (AFAIR), 6 hours,  
but stopped this practice sometime before 2005 -- unfortunately it has  
become ingrained wisdom that is hard to shift.

The other part of the story is applications that call gethostbyname()  
(or equivalent) at startup / initial connection and keep the result  
until they die. This used to be even more common, but now that  
(apparently) all the world is a webbrowser this isn't as common....


> Does anybody actually do this? Because it keep being brought up by  
> some peopel as to why things like GSLB don't work.
> -- 
> Simon Lyall  |  Very Busy  |  Web: http://www.darkmere.gen.nz/
> "To stay awake all night adds a day to your life" - Stilgar | eMT.
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