TTL problem wih bind 8.3.6 cache

Jim Reid jim at rfc1035.com
Thu Apr 28 21:32:33 UTC 2005


On Apr 28, 2005, at 20:23, Matus UHLAR - fantomas wrote:

> It seems that BIND updates the NS record for the zone, as long as it 
> came in
> AUTHORITY section, but does NOT update the A record, because it came in
> ADDITIONAL section. Then, in 38385 seconds, bind will know that
> multimedia.sk is delegated to 'opal.multimedia.sk' but won't know its 
> IP
> address and thous won't be able even to find it.
>
> Can anyone tell me, if this behaviour is correct? Did I made a mistake
> somwehere? Or, where lies the main problem, except the fact that the 
> domain
> really should be delegated to more servers, probably in more domains?

There is nothing wrong with BIND's behaviour in the scenario you 
outlined. When the TTL for
opal.multimedia.sk expires, the name will be removed from the name 
server's cache. If it is then asked for that name again, the name 
server will resolve it in precisely the same way as it resolved the 
name before it was in the cache. ie By iteratively querying the root 
(maybe) and .sk name servers, following the delegation chain.

The difference in TTL values you showed is because you queried 
different name servers. In the first examples,
you're querying a caching server. It's populating the Additional 
Section of the reply with relevant data from its cache. Any TTL values 
will reflect the time to live that cached data had at  the moment it 
was fetched from cache and put in the answer. You presumably got a 
longer TTL for the MX record because this hadn't been cached so your 
server had to query an authoritative server to get that answer and then 
cache it. In the second examples, you're querying the authoritative 
server for opalmultimedia.sk. The TTL values for names in that zone 
will not change unless you modify the entries in the zone file.

And yes, your zone really should have a second name server. Please read 
and follow the advice in RFC2182.



More information about the bind-users mailing list