Re: SCAN lookup request goes to old DNS server

From: Mark Bobak <>
Date: Tue, 11 Mar 2014 23:14:01 +0000
Message-ID: <>

I wonder if nscd caches the name server IP?

$ service nscd stop

(You didn't mention O/S or O/S version. That will work for RHEL6/OL6)


From: Stalin Subbiah <<>> Reply-To: "<>" <<>> Date: Tuesday, March 11, 2014 at 5:47 PM To: "<<>>" <<>> Subject: SCAN lookup request goes to old DNS server


We recently made some changes to names server which hosts SCAN IPs for a RAC cluster. There is no change in domain name, SCAN Ips or anything, it's just we added another secondary DNS server and added it's IP (10.124.x.x) as the first names server in resolve.conf in all DB nodes, so that transition becomes seamless when we phase out older names server (10.119.x.x).

DB Node --
-bash-3.2$ more /etc/resolv.conf

nameserver 10.124.x.x
nameserver 10.119.x.x

-bash-3.2$ nslookup<>
Server: 10.124.x.x
Address: 10.124.x.x#x

Name:<> Address: 10.119.x.x
Name:<> Address: 10.119.x.x
Name:<> Address: 10.119.x.x

As you can see lookup for SCAN in OS seems to pick the right names server for the requests, however network team is seeing scan lookup traffic to 10.119.x.x names server from db node(s). We had 10.119.x.x as the first entry in resolve.conf before and that's the names server we are phasing it out.

Does anyone know if clusterware is caching names server somewhere? I didn't expect this to be case at first but saw this behavior after making this change to the cluster. I also tried dumping OCR but didn't see any info there.


-- Received on Wed Mar 12 2014 - 00:14:01 CET

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