SUMMARY: Reverse DNS cache on Solaris 9 - where it is?

From: Brandon Haberfeld <BrandonH_at_investec.co.za>
Date: Mon Jan 16 2006 - 05:42:36 EST
The solution was the obvious /etc/rc2.d/S76nscd which needed to be
restarted. I was having a blond Monday.
Thankx to Drew Skinner, Eugene Schmidt and Michael Schneider

Regards

Brandon Haberfeld
Investec Bank Limited
brandonh@investec.co.za



-----Original Message-----
From: Brandon Haberfeld
Sent: 16 January 2006 10:46
To: sunmanagers@sunmanagers.org
Subject: Reverse DNS cache on Solaris 9 - where it is?


Hi Gurus

I am running vanilla Solaris 9 and had a strange situation where a user
pc changed IP addresses and thereafter a forward DNS lookup to that
desktop returned the correct IP address, but the reverse lookup shown
under a traceroute command below returned the wrong PC name. There is no
static hosts file entry although when I created one and then removed it,
the problem went away. This implies that somewhere in solaris there is a
reverse DNS lookup cache which updated after the static entry was
created and referenced.

Does anyone know how to flush such a cache if it exists.
I am not running "named" / "bind" or any other DNS server on the box -
pure dynamic DNS via the resolv.conf file which looks like this:

	domain investec.co.za
	retry:1
	retrans:1
	nameserver 10.100.0.72
	nameserver 10.100.2.73

And the nssswitch.conf references the hosts file before the dns.
	hosts:      files dns

Here's the output of the problem: Forward nslookup from the server
returns the correct ip address
	riskrw1:root:~> nslookup i72434-XP
	Server:  dccorpjhb01.corp.investec.com
	Address:  10.100.0.72
	Name:    i72434-XP.investec.co.za
	Address:  10.100.78.117

Traceroute, however, which uses reverse lookup, returned for that name,
the IP address but resolved the name incorrectly from some cache.
riskrw1:root:~> traceroute i72434-XP traceroute to
i72434-XP.investec.co.za (10.100.78.117), 30 hops max, 40 byte packets
1  10.100.76.1 (10.100.76.1)  0.409 ms  0.267 ms  0.288 ms  2
i60828-w2k.za.corp.investec.com (10.100.78.117)  0.284 ms  0.193 ms
0.193 ms

I should also mention that the problem did not occur on servers where
this user had never logged on before further indicating the a reverse
DNS cache is being used by Solaris 9 - but where is it and how can one
flush it immediately when user PC ip's change in the corporate DNS
server. Any help would be appreciated. Please ignore the non-disclosure
notice which my corporation's mail server will tack on the end of this
mail.

Regards
Brandon
Investec Bank Limited
brandonh@investec.co.za
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Received on Mon Jan 16 05:41:23 2006

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