Sortlist and individual zones

Kevin Darcy kcd at
Wed Jan 28 16:30:32 UTC 2004

Brian Miller wrote:

>I have been asked to look into setting up out companies internal DNS to
>return different IP addreesses for a specific RR based upon the location of
>the client (clients in each state get the IP address of a local server).
>I can differentate between the clients easily enough based on their network,
>and it looks like I could do what's needed with the "sortlist" option.
>Currently our DNS's are running pretty busy, so I don't want all queries
>being passed via the sortlist as over 99% of the queries don't need
>sorting. Is it possible to have the sortlist applied only to a single zone?
>We are running BIND 8, not 9 if that makes any difference.
No, I believe sortlist is a global option. Or, possibly it might be a 
view-specific option, but I don't think that really helps you.

I can't imagine you'd have much of a performance hit from a sortlist, 
even a complicated one, unless you have a lot of other multiple-A-record 
names (aka "round-robin"s) being looked up in addition to the specific 
RR you mentioned. If a DNS response has only 1 A record, then there 
should be no sortlist processing whatsoever.

BTW, if you have all of these clients scattered all over the place, do 
you have local caching servers for them to use (these can be easily 
co-located on nearby web servers, directory servers, etc. if necessary). 
If you haven't distributed your name-resolution resources, then perhaps 
that helps explain why your servers are overloaded. The other common 
cause of server overloading is of course TTL settings that are too low.

- Kevin

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