nscd and DNS cache

[Ed Greshko]

On 05/16/2012 11:47 PM, JD wrote:
> Interesting point. Hard to believe that  most domain controllers would that.
> Must be a small  percentage? 

I have no idea what percentage it may be.  But 300 seems a bit low....

I'd have to do some research but it very well may be that sites set their TTL's low
in an attempt to balance DNS server load with load balancing (round robin) of their
web sites.

It seems that the TTL for www.cnn.com is set to 150 seconds.

I'd have to check....  But when you do a look up on www.cnn.com it will return 4 IP
addresses.  Now, since bind would have that in its cache it wouldn't have to send out
a query.  What I don't know is if an application would make a request would the list
be returned in the same order every time to the requesting application?   In other
words, if the TTL is not set low, would that defeat the round robin technique.

Interesting things to investigate.....if I really had the time.

-- 
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