How to correct reverse DNS error on utils diagnose test?

[jamize]

             We were working an issue in our Publisher and Subscribers and performed a "utils diagnose test" on each through the command line.  It passed everything but reverse dns lookup.  Does anyone know how to fix that type error?  Thanks in advance.  We are running CUCM 8.6(2a)SU3.     

[Jaime Valencia]

Just make sure they're properly added in the forward and reverse lookup zones in your DNS.

HTH

java

if this helps, please rate

www.cisco.com/go/pdihelpdesk

[jamize]

How do we find out what the test is trying to lookup in dns that is failing?  Our network group  provided the following.

c:\Windows\System32>dig +short -x 10.250.10.10

cmp1.hs.uab.edu

[yahsiel2004]

Your DNS Admins will need to add the reverse lookup for your server. Example below

Forward Lookup

A cucmpub.local 10.0.0.1

Reverse Lookup

PTR 10.0.0.1 cucmpub.local

HTH

Regards,

Yosh

[jamize]

Can you please provide the entry they will need to for us for the following?

10.250.10.10 is the ip address of the publisher.

cmp1.hs.uab.edu is the host name

Thanks,

Jeff

[yahsiel2004]

PTR 10.250.10.10 cmp1.hs.uab.edu

HTH

Regards,

Yosh

[jamize]

To clarify, we would need the following entries???

PTR 10.250.10.10 cmp1.hs.uab.edu

PTR 10.250.10.11 cms1.hs.uab.edu

PTR 10.250.10.12 cms2.hs.uab.edu

PTR 10.250.10.13 cms3.hs.uab.edu

PTR 10.250.10.14 cms4.hs.uab.edu

Thanks,

Jeff

[Jonathan Schulenberg · Accepted solution]

Yes and it's important there is only one PTR record per IP address. If you're using a non-Windows DNS infrastructure it's likely to look more like this:

10.10.250.10.in-addr.arpa   PTR  cmp1.hs.uab.edu

Note that the IPv4 octets are reversed.

Please remember to rate helpful responses and identify helpful or correct answers.

[yahsiel2004]

Jonathan,

+5 that's some good information.

HTH

Regards,

Yosh

[Nizam.Ahmed]

Hi Jonathan,

Nice instruction. We have added like this 10.10.250.10.in-addr.arpa.  PTR  cmp1.hs.uab.edu.com for reverse lookup in centos dns server. but unfortunately fail in reverse lookup while we dig for testing (But forward lookup is OK). In cucm server an error 'DNS server unreachable' is showing. 'Reverse Lookup DNS failed' is showing debug test.

But  this type of problem is not heppening in windows server.

Would you/anybody can help me the solution.

Thanks in advance and i'll give rate 5 :)

Regards

Nizam

[Jonathan Schulenberg]

What I typed above is how the PTR record should look when queried from a tool such as dig. Creating the record is more involved than that. For example, you will likely need to create a zone file and reference it in named.conf and then define the PTR record within that. Ask your DNS admin for assistance here.

[jamize]

Yosh/Jonathan - You were both correct.  What we found was they needed our ad entry added not just our hs entry.  We changed the names to cmp1.ad.hs.uab.edu and it worked.  We have also pointed cmp1.hs.uab.edu to the ad entry to ensure we don't miss any possible entries.

Thank you both for the assistance.

Jeff