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Old 04-15-2015, 02:26 AM   #1
vanagpure
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Registered: Apr 2015
Posts: 3

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nslookup unable to resolve hostname


Hi All,

In our 12.1.3 EBS environment, database and application are on the same machine. OS is RHEL 5.7 64 bit. This is a test instance and it was working fine till last Friday when suddenly application startup scripts started failing with database connectivity error. No changes were done from db/application side. The database and listener were up and I was able to connect from apps tier via sqlplus. But JDBC connection is failing. Now I have discovered this:



[applmgr@uat ~]$ nslookup xx.xx.xx.83

Server: xx.xx.xx.4

Address: xx.xx.xx.4#53



xx.xx.xx.172.in-addr.arpa name = abc.xyz.net.



[applmgr@uat ~]$

[applmgr@uat ~]$

[applmgr@uat ~]$ nslookup abc.xyz.com (This is the hostname in /etc/hosts and it was working fine till fridy)

Server: xx.xx.xx.4

Address: xx.xx.xx.4#53



** server can't find abc.xyz.com: NXDOMAIN



The hostname in /etc/hosts is abc.xyz.com but nslookup is hitting at abc.xyz.net. Our sysadmin/network guys say they have not made any changes. So how can this happen?

Regards,
Vinod
 
Old 04-15-2015, 02:43 AM   #2
Bruce783
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Registered: Apr 2015
Location: Kommetjie, Cape Town, ZA
Distribution: Gentoo
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nslookup will not use the local hosts file to resolve hostnames. It will send the query to the name server. The name server does not have an entry for abc.xyz.com so it is returning NXDOMAIN.

Try and ping abc.xyz.com (just for DNS resolution purposes)...

Ask the sysadmin guys about the reverse DNS.

Last edited by Bruce783; 04-15-2015 at 02:47 AM. Reason: added additional details
 
Old 04-15-2015, 03:34 AM   #3
vanagpure
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Registered: Apr 2015
Posts: 3

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ping abc.xyz.com is working from the server as well as my desktop. And strangely, I am able to ping abc.xyz.com as well as abc.xyz.net!
 
Old 04-15-2015, 05:24 AM   #4
pan64
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Location: Hungary
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nslookup can use different nameservers. Probably you need to configure it to use another one.
 
  


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