topic Re: how to check dns cache in Operating System - Linux

how to check dns cache

Maaz — Sat, 25 Nov 2006 12:57:28 GMT

name server: bind 9
name server type: cache-only
OS: rhel 4

how to check cache of DNS server cache ? any command ?

and also how to check/clear the dns client-cache ? in windows xp to check dns client cache 'ipconfig /displaydns' to clear cache 'ipconfig /flushdns'.. wana know linux equivalent.

Regards
Maaz

Re: how to check dns cache

Ivan Krastev — Sun, 26 Nov 2006 06:10:25 GMT

You can flush/clear dns cache on clients with restarting ncsd daemon: /etc/init.d/ncsd restart

regards,
ivan

Re: how to check dns cache

Ragu_3 — Mon, 27 Nov 2006 00:26:41 GMT

You can take a dump by doing "rndc dumpdb", the cache dump is saved as a file at '/var/cache/bind'. Do a "rndc --help" for more info.

Re: how to check dns cache

Abdulla Fayez C.E.V. — Tue, 28 Nov 2006 07:21:06 GMT

Hi Maaz,

You can use this command.
#ipconfig /flushdns

Fayez

Re: how to check dns cache

Vitaly Karasik_1 — Tue, 28 Nov 2006 09:31:30 GMT

I don't think that "normal" linux resolver library has a cache.
There is "nscd" (Name Service Cache Daemon). If you run it, you should restart nscd for cleaning its cache.

As for cache of bind9 - with "rndc" (http://www.bind9.net/manual/bind/9.2.5/Bv9ARM.ch03.html) you can check and clean dns cache.