Negative caching

[Cricket Liu]

Robert T. Clift <rclift at nswc.navy.mil> wrote in message
news:<9908311037.ZM1201 at mailsrvx>...
> I've been having a problem with one of our remote sites and name
resolution. We
> use tcp_wrappers to control telnet access and it requires a correct dns
lookup
> before completing the connection, if the site for some reason is
unresolvable
> it seems to stay unresolvable for an hour or more not allowing access. If
I
> restart the named service(8.1.2) it works fine. I read where the default
cache
> is set to one hour. Should I lower this value? Thanks,

With BIND 8.1.2, you can't change the negative caching TTL.  It's ten
minutes, hardcoded.  With BIND 8.2+, the name server uses the seventh SOA
RDATA field as the negative caching TTL, per RFC 2308, and you can cap that
using max-ncache-ttl, as in:

options {
    max-ncache-ttl 2;    // Two minutes
};

Still, I wonder if that's really the problem you're seeing.

cricket

Acme Byte & Wire
cricket at acmebw.com
www.acmebw.com

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