[j-nsp] Re: Juniper DNS cache

Warren Kumari warren at kumari.net
Mon Dec 12 18:52:05 EST 2005

Yes, you appear to be correct -- something that lots of people don't  
realize though is that many (most?) long running processes only call  
gethostbyname (or something similar) once.

I have seen many cases where people list the DNS names for their  
RADIUS / Syslog / etc servers and then become unhappy / confused when  
they update DNS and nothing changes....


On Dec 10, 2005, at 8:09 AM, sthaug at nethelp.no wrote:

>>> Juniper does not operate as a caching nameserver, therefore it  
>>> has no DNS
>>> cache. It will send new queries to its configured nameservers  
>>> every time,
>>> so if something isn't updating, it is the nameservers you are using.
>> Even if a *nix box doesn't run BIND, djbdns or other caching
>> nameservers, many run nscd ("name service cache daemon"), which  
>> caches
>> all libc calls to the resolver. The FreeBSD under-the-hood in the
>> routing engine has nscd enabled or disabled, and even if nscd is
>> running what is configured in nscd.conf and nssswitch.conf  ?
> As far as I know, what's under the hood is based on FreeBSD 4.x, which
> has no nscd. Thus I believe the answer given earlier is correct, JunOS
> does *not* cache DNS replies. A simple traceroute run several times on
> the router, with tcpdump running on the configured name server,  
> appears
> to confirm this.
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> http://puck.nether.net/mailman/listinfo/juniper-nsp

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