CUCM 11.5 WARNING: DNS unreachable

[cristian.munoz]

Hi Guys

I have a issue with the DNS: In the CUCM web admin, it show WARNING: DNS unreachable.

I have the follow tests:

Starting diagnostic test(s)
===========================
test - disk_space          : Passed (available: 1207 MB, used: 12475 MB)
skip - disk_files          : This module must be run directly and off hours
test - service_manager     : Passed
test - tomcat              : Passed
test - tomcat_deadlocks    : Passed
test - tomcat_keystore     : Passed
test - tomcat_connectors   : Passed
test - tomcat_threads      : Passed
test - tomcat_memory       : Passed
test - tomcat_sessions     : Passed
skip - tomcat_heapdump     : This module must be run directly and off hours
test - validate_network    : Reverse DNS lookup mismatch
test - raid                : Passed
test - system_info         : Passed (Collected system information in diagnostic              

             log)
test - ntp_reachability    : Passed
test - ntp_clock_drift     : Passed
test - ntp_stratum         : Passed
skip - sdl_fragmentation   : This module must be run directly and off hours
skip - sdi_fragmentation   : This module must be run directly and off hours

03-01-2018 12:19:31 validate_network:     Hostname: [ANDROMEDA]
03-01-2018 12:19:31 validate_network:     found pub name [ANDROMEDA]
03-01-2018 12:19:31 validate_network:     result: 7, message: Reverse DNS lookup mismatch

********************

show network eth0:
DNS
Primary      : 10.175.0.113       Secondary  : 10.175.0.40
Options      : timeout:5 attempts:2

admin:utils network ping 10.175.0.113
PING 10.175.0.113 (10.175.0.113) 56(84) bytes of data.
64 bytes from 10.175.0.113: icmp_seq=1 ttl=126 time=1.07 ms
64 bytes from 10.175.0.113: icmp_seq=2 ttl=126 time=1.00 ms
64 bytes from 10.175.0.113: icmp_seq=3 ttl=126 time=0.990 ms
64 bytes from 10.175.0.113: icmp_seq=4 ttl=126 time=1.19 ms

--- 10.175.0.113 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3014ms
rtt min/avg/max/mdev = 0.990/1.068/1.195/0.080 ms


admin:utils network ping 10.175.0.40
PING 10.175.0.40 (10.175.0.40) 56(84) bytes of data.
64 bytes from 10.175.0.40: icmp_seq=1 ttl=127 time=0.495 ms
64 bytes from 10.175.0.40: icmp_seq=2 ttl=127 time=0.845 ms
64 bytes from 10.175.0.40: icmp_seq=3 ttl=127 time=0.879 ms
64 bytes from 10.175.0.40: icmp_seq=4 ttl=127 time=0.742 ms

--- 10.175.0.40 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3001ms
rtt min/avg/max/mdev = 0.495/0.740/0.879/0.151 ms

Any idea?

TIA
Cristian

[acampbell]

Hi,

Look at this posting.

I do not see your domain in the "show network eth0" - output

https://supportforums.cisco.com/t5/ip-telephony/cucm-warning-dns-unreachable/td-p/2714928

[cristian.munoz]

Dear Alex

It´s have DNS. I didn´t write.

[acampbell]

Hi,

 Look at this posting.

I do not see your domain in the "show network eth0" - output

https://supportforums.cisco.com/t5/ip-telephony/cucm-warning-dns-unreachable/td-p/2714928

[Aeby Vinod]

Your DNS server is reachable, make sure forward and reverse lookup entries in your DNS server are correct.

Forward Lookup

A cucm.local 10.10.10.10

Reverse Lookup

PTR 10.10.10.10 cucm.local

Please rate if found helpful

Regards,
Aeby

[cristian.munoz]

Dear Aeby

Thank you for your answer. I´m going to talk the DNS admin and try explaining it to him. Hard task is waiting for me.  :)

Regards,

[Sandro Nardi]

The message
test - validate_network    : Reverse DNS lookup mismatch

03-01-2018 12:19:31 validate_network:     result: 7, message: Reverse DNS lookup mismatch
are showing a mismatch between reverse and forward dns record.

you can test the resolution with "nslookup"
setting the server an resolving the name and the ip address of the CUCM and vice versaCMD prompt

[cristian.munoz]

Dear Sandro

Thank you . I´m going to test and then comments the results.

Regards

[jesus.delgado@hshs.org]

I conducted an nslookup for my 2 DNS server IPs and CUCM publisher; the 2 DNS servers resolved but the CUCM publisher did not, it returned an error indicating it could not find the IP address: Non-existent domain.

Then, I reached out to my server team and provided them the results of the nslookup.

My server team created a pointer (PTR) record, this type of record resolves IP address to domain or host name; PTR records are utilized for reverse DNS lookups. 

Next, I accessed the CLI on my CUCM publisher and entered the following commands:

show status

show network eth0

show network cluser

utils diagnose test

Finally, I logged out of CUCM.

Issue resolved!