does bind caches no replies ?

Ladislav Vobr lvobr at ies.etisalat.ae
Sun Feb 16 02:53:33 UTC 2003


this option is helpfull if you get some answer, like NXDOMAIN, but in my case I don't get any
responses from any of the athoritative NS for that domain, temporarily all NS are unreachable.
Best Regards
Ladislav Vobr
Etisalat, UAE

NT Canuck wrote:

> "Simon Waters" <Simon at wretched.demon.co.uk> wrote in message news:b2laig$c1mo$1 at isrv4.isc.org...
>
> > > I did some research but could not discovered how often bind
> > > is retrying or what are the time-outs.
>
> dns/etc/named.conf....
> under "options"
> max-ncache-ttl 30;
>
> In above line the negative cache-ttl is set to only 30 seconds,
> above setting is from one of my personal resolvers.
> I tried the .pk site you mentioned...2-3 seconds for a not found.
> http://www.infopak.gov.pk/
>
> Actually..this is unusual and quite a problem they should fix.
> http://www.infopak.gov.pk/ no
> http://www.pak.gov.pk/  no
>
> http://www.finance.gov.pk yes
> http://www.punjab.gov.pk/ yes
> http://www.cbr.gov.pk/ yes
>
> hmm...sometimes a cc tld is hosted,
> not all cc tld or sites are in country of origin.
>
> this one is coming in ok
> http://www.nopop.net/
>
> perhaps a note to the webmasters or host isp?
>
> []
>
> > I think you have to hope that the authors of the clients will
> > build in exponential back off or similar safeguards, like most
> > mail servers, or scale your DNS for a worst case scenario.
>
> This is getting tougher...but you are correct,
> most of the items have to be some hard-coded handling.
>
> > Don't be shy in suggesting such sites try an offsite DNS server,
> > or longer TTL.
>
> As you mentioned earlier...too long a neg ttl may cut into
> clients retries, and also into site queries where remote
> server or dns proxy uses a dynamically updated dns.
>    For that matter...some ISP's or dns servers don't
> configure or correctly obey remote server ttl's...so this
> could also be the case... in some similar situations to topic.
>
> 'Seek and ye shall find'
> NT Canuck
> http://ntcanuck.com


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