Negative Caching trouble

[Kevin Darcy]

Jaysheel Mehd wrote:

>Hey Everyone,
>
>Every now and then I am stumbling into the problem of negative caching 
>on my DNS server. The intranet DNS server seems to resolve the MX, A 
>records of the domain absolutely fine. The domain in question here is 
>shns.com.cn. While the external DNS server seems to fumble to get the 
>records.
>
>The DNS records of the domain shns.com.cn seems absolutely fine. Also, 
>my intranet and extranet servers run the same version of BIND. It is 
>BIND-9.2.1.
>
>Once, I dump the cache everything works fine. Why the DNS server should 
>behave in such a fashion and what should be done to resolve it permanently?
>
I'm not sure what you mean by "dump the cache". Flush the cache? Reload? 
Restart?

In any case, next time this happens, *dump* the cache (via rndc dumpdb) 
and maybe you'll be able to diagnose what's wrong with shns.com.cn. From 
what I can see, the only issue is that the NS records of the zone don't 
match the delegated NS records. But since none of those names are in the 
shns.com.cn domain, there's no "chicken-and-egg" problem, so I don't see 
how it could lead to the symptoms you're seeing. BIND 9 has query 
restart, so even when the A records time out of the cache before the NS 
records, it should be able to fetch new A records...

- Kevin