DNS SRV Record Issue

[Nikhil Jayan Kandampully]

HI All,

VCS X7.2.2

I am facing some problem with DNS SRV Records. Please see the below mentioned logs which i collected from EX90.

--------------------------------------------------------------------------------------------------

Jul  2 12:58:27 ppc appl: 81496.55 DnsLocator !ER DnsLocator(id=0x4837c910) ran out of strategies

Jul  2 12:58:32 ppc appl: 81501.55 DnsLocator I: locate(): we've failed, give up for now (throttleTimerExpired(id:123184))

Jul  2 12:58:32 ppc appl: 81501.55 DnsLocator I: naptrQuery(s=video1.telecom.qat.gov.qa)

Jul  2 12:58:32 ppc appl: 81501.55 DnsLocator I: recv() 0 naptr records

Jul  2 12:58:32 ppc appl: 81501.55 DnsLocator I: srvQuery(s=_sips._tcp.video1.telecom.qat.gov.qa)

Jul  2 12:58:32 ppc appl: 81501.56 DnsLocator I: recv() 0 srv records

Jul  2 12:58:32 ppc appl: 81501.56 DnsLocator I: srvQuery(s=_sip._tcp.video1.telecom.qat.gov.qa)

Jul  2 12:58:32 ppc appl: 81501.56 DnsLocator I: recv() 0 srv records

Jul  2 12:58:32 ppc appl: 81501.57 DnsLocator I: srvQuery(s=_sip._udp.video1.telecom.qat.gov.qa)

Jul  2 12:58:32 ppc appl: 81501.57 DnsLocator I: recv() 0 srv records

Jul  2 12:58:32 ppc appl: 81501.57 DnsLocator I: aQuery(s=video1.telecom.qat.gov.qa)

Jul  2 12:58:32 ppc appl: 81501.58 DnsLocator I: recv() 0 a records

Jul  2 12:58:32 ppc appl: 81501.58 DnsLocator !ER DnsLocator(id=0x4837c910) ran out of strategies

Jul  2 12:58:37 ppc appl: 81506.58 DnsLocator I: locate(): we've failed, give up for now (throttleTimerExpired(id:123191))

Jul  2 12:58:37 ppc appl: 81506.58 DnsLocator I: naptrQuery(s=video1.telecom.qat.gov.qa)

Jul  2 12:58:37 ppc appl: 81506.58 DnsLocator I: recv() 0 naptr records

-----------------------------------------------------------------------------------------------------

Jul  1 12:16:29 ppc appl: 110.40 SipReg W: Transport failed to send registration (sipexcept: 6 DNS Failure)

-----------------------------------------------------------------------------------------------------

Below are the SRV Records which i have updated on my local DNS Server. when i do the DNSLOOKUP from the laptop (Laptop is connected to the same EX90 network)  i can see SRV Records are getting resolved. i am sure the SRV Records are resolvable from the EX90 Network. i tried to resolve the same SRV Records by using VCS DNSLook up tool, and it's resolvable from there as well.

DNS SRV RECORD IN CUSTOMER CORPORATE DNS SERVER FOR ENDPOINT   REGISTRATION TO  VCSC-CLUSTER
Service	_Protocol	Name (service record)	TTL	Class	Priority	Weight	Port	Host	Target( A-record)	IP Address
_sip	_udp	video1.telecom.qat.gov.qa	86400	IN	10	100	5060	_sip._udp.video1.telecom.qat.gov.qa	vcsc01.telecom.qat.gov.qa	10.150.10.10
_sip	_tcp	video1.telecom.qat.gov.qa	86400	IN	10	100	5060	_sip._tcp.video1.telecom.qat.gov.qa	vcsc01.telecom.qat.gov.qa	10.150.10.10
_sips	_tcp	video1.telecom.qat.gov.qa	86400	IN	10	100	5061	_sips._tcp.video1.telecom.qat.gov.qa	vcsc01.telecom.qat.gov.qa	10.150.10.10
_h323rs	_udp	video1.telecom.qat.gov.qa	86400	IN	10	100	1719	_h323rs._udp.video1.telecom.qat.gov.qa	vcsc01.telecom.qat.gov.qa	10.150.10.10
_h323ls	_udp	video1.telecom.qat.gov.qa	86400	IN	10	100	1719	_h323ls._udp.video1.telecom.qat.gov.qa	vcsc01.telecom.qat.gov.qa	10.150.10.10
_h323cs	_tcp	video1.telecom.qat.gov.qa	86400	IN	10	100	1720	_h323cs._tcp.video1.telecom.qat.gov.qa	vcsc01.telecom.qat.gov.qa	10.150.10.10
_sip	_udp	video1.telecom.qat.gov.qa	86400	IN	10	100	5060	_sip._udp.video1.telecom.qat.gov.qa	vcsc02.telecom.qat.gov.qa	10.150.11.10
_sip	_tcp	video1.telecom.qat.gov.qa	86400	IN	10	100	5060	_sip._tcp.video1.telecom.qat.gov.qa	vcsc02.telecom.qat.gov.qa	10.150.11.10
_sips	_tcp	video1.telecom.qat.gov.qa	86400	IN	10	100	5061	_sips._tcp.video1.telecom.qat.gov.qa	vcsc02.telecom.qat.gov.qa	10.150.11.10
_h323rs	_udp	video1.telecom.qat.gov.qa	86400	IN	10	100	1719	_h323rs._udp.video1.telecom.qat.gov.qa	vcsc02.telecom.qat.gov.qa	10.150.11.10
_h323ls	_udp	video1.telecom.qat.gov.qa	86400	IN	10	100	1719	_h323ls._udp.video1.telecom.qat.gov.qa	vcsc02.telecom.qat.gov.qa	10.150.11.10
_h323cs	_tcp	video1.telecom.qat.gov.qa	86400	IN	10	100	1720	_h323cs._tcp.video1.telecom.qat.gov.qa	vcsc02.telecom.qat.gov.qa	10.150.11.10

The DNS Resolution failure for the SRV Records issue is happening for all the devices includes Endpoints and other core components. But the SRV Records are resolvable through DNSLook UP Tool from laptop and VCS.

Thanks & Regards,

Nikhil Jayan

[Paulo Souza]

Well, for me, all the configuration seems to be right. There is only one difference comparing to Cisco documentation, the parameter "weight" should be 10 rather than 100. Not sure if this could be a problem, but you could try to use 10.

Paulo Souza

Please rate replies and mark question as "answered" if applicable.

[Martin Koch]

The priority and weitght should not make a problem.

The more interesting part here would be to know the TC version running on the EX90.

I would check that the network and DNS is ok on the endpoint. I would recomend TC6.1.2 or TC5.1.7

Can you login as root to the endpoint and do a

tcpdump -nl -s0  port 53

and paste the output? that should tell us a bit more on how the lookup fails.

I would also recomend trying to use the dns server you have (for example with a windows computer

using the same dns) and do a lookup of the srv records.

Like:

nslookup -type=srv video1.telecom.qat.gov.qa 8.8.8.8

replace the 8.8.8.8 with the ip of your internal DNS.

Please paste this output as well.

Its important that it points to an A record and not directly to an ip,

also check that the A record it points to can be resolved.

And trust me, there are often firewalls, so what one IP or computer can see mght not be seen by the other one

and sure, the proper dns server needs to be set up on the endpoint.

Do you use dhcp or static ip setup?

try to see with a (logged in as admin via ssh)

xstat // dns

and see that it is right

also try to do a

systemtools network ping vcsc01.telecom.qat.gov.qa

If you get something like:

ping: Couldn't look up host "vcsc01.telecom.qat.gov.qa".

someting really fishey is going on with your DNS :-)

[asafayan]

Martin,

Thorough and helpful response as usual.  +5 points.

Amir