DNS Cache module

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DNS Cache module

Ben Newlin

Hello,

 

We use the DNS cache module to reduce the time spent querying DNS records. We recently had a customer call failing and we traced the failure to the customer using an FQDN in the Record-Route header. On the ACK, OpenSIPS appeared to not be able to resolve the domain even though it had been successfully resolved on the initial request. I found the log for the DNS Cache module and noticed that the value it was inserting was empty:

 

INFO:dns_cache:put_dnscache_value: putting key [dnscache_customer.domain.com_a] with value [] ttl = 60

 

This prompted me to examine all of our logs and I found that the value for these DNS Cache logs is always empty, regardless of the domain. It appears the records are not being serialized properly into the cache.

 

The DNS resolution must be succeeding or all of our requests using DNS would be failing, but I have also verified the domains all can be resolved manually on the same box:

 

$ nslookup customer.domain.com

Server:       10.27.0.2

Address:      10.27.0.2#53

 

Non-authoritative answer:

Name:  customer.domain.com

Address: 10.27.172.132

Name:  customer.domain.com

Address: 10.27.192.211

Name:  customer.domain.com

Address: 10.27.255.53

 

Any thoughts? Is there more information I can obtain to determine the cause?

 

Ben Newlin


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Re: DNS Cache module

Bogdan-Andrei Iancu-2
Hi Ben,

IMO, the log itself is broken as the data to be cached is not printable ....so the logs you see may be misleading.

When you say "OpenSIPS appeared to not be able to resolve the domain", you mean OpenSIPS is not doing any attempt to solve the FQDN, or you mean OpenSIPS is loading from cash something wrong ?

Regards,
Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
  https://www.opensips-solutions.com
OpenSIPS Summit 2019
  https://www.opensips.org/events/Summit-2019Amsterdam/
On 12/06/2018 10:17 PM, Ben Newlin wrote:

Hello,

 

We use the DNS cache module to reduce the time spent querying DNS records. We recently had a customer call failing and we traced the failure to the customer using an FQDN in the Record-Route header. On the ACK, OpenSIPS appeared to not be able to resolve the domain even though it had been successfully resolved on the initial request. I found the log for the DNS Cache module and noticed that the value it was inserting was empty:

 

INFO:dns_cache:put_dnscache_value: putting key [dnscache_customer.domain.com_a] with value [] ttl = 60

 

This prompted me to examine all of our logs and I found that the value for these DNS Cache logs is always empty, regardless of the domain. It appears the records are not being serialized properly into the cache.

 

The DNS resolution must be succeeding or all of our requests using DNS would be failing, but I have also verified the domains all can be resolved manually on the same box:

 

$ nslookup customer.domain.com

Server:       10.27.0.2

Address:      10.27.0.2#53

 

Non-authoritative answer:

Name:  customer.domain.com

Address: 10.27.172.132

Name:  customer.domain.com

Address: 10.27.192.211

Name:  customer.domain.com

Address: 10.27.255.53

 

Any thoughts? Is there more information I can obtain to determine the cause?

 

Ben Newlin



_______________________________________________
Users mailing list
[hidden email]
http://lists.opensips.org/cgi-bin/mailman/listinfo/users


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Re: DNS Cache module

Ben Newlin

Bogdan,

 

That had occurred to me as well. I have verified testing locally that when successful the value is printed in the log. I have also verified manually on the system with the error that the key does exist in the cache, but the value in the cache is empty, just as in the log. That is what I believe is causing the failure, the lookup from the cache is successful (the key exists) but the value is empty, so OpenSIPS cannot route.

 

I have attempted increasing the logging on the system, but it appears the dns_cache module does not log anything further of use.

 

Ben Newlin

 

From: Bogdan-Andrei Iancu <[hidden email]>
Date: Friday, December 7, 2018 at 12:21 PM
To: OpenSIPS users mailling list <[hidden email]>, Ben Newlin <[hidden email]>
Subject: Re: [OpenSIPS-Users] DNS Cache module

 

Hi Ben,

IMO, the log itself is broken as the data to be cached is not printable ....so the logs you see may be misleading.

When you say "OpenSIPS appeared to not be able to resolve the domain", you mean OpenSIPS is not doing any attempt to solve the FQDN, or you mean OpenSIPS is loading from cash something wrong ?

Regards,

Bogdan-Andrei Iancu
 
OpenSIPS Founder and Developer
  https://www.opensips-solutions.com
OpenSIPS Summit 2019
  https://www.opensips.org/events/Summit-2019Amsterdam/

On 12/06/2018 10:17 PM, Ben Newlin wrote:

Hello,

 

We use the DNS cache module to reduce the time spent querying DNS records. We recently had a customer call failing and we traced the failure to the customer using an FQDN in the Record-Route header. On the ACK, OpenSIPS appeared to not be able to resolve the domain even though it had been successfully resolved on the initial request. I found the log for the DNS Cache module and noticed that the value it was inserting was empty:

 

INFO:dns_cache:put_dnscache_value: putting key [dnscache_customer.domain.com_a] with value [] ttl = 60

 

This prompted me to examine all of our logs and I found that the value for these DNS Cache logs is always empty, regardless of the domain. It appears the records are not being serialized properly into the cache.

 

The DNS resolution must be succeeding or all of our requests using DNS would be failing, but I have also verified the domains all can be resolved manually on the same box:

 

$ nslookup customer.domain.com

Server:       10.27.0.2

Address:      10.27.0.2#53

 

Non-authoritative answer:

Name:  customer.domain.com

Address: 10.27.172.132

Name:  customer.domain.com

Address: 10.27.192.211

Name:  customer.domain.com

Address: 10.27.255.53

 

Any thoughts? Is there more information I can obtain to determine the cause?

 

Ben Newlin




_______________________________________________
Users mailing list
[hidden email]
http://lists.opensips.org/cgi-bin/mailman/listinfo/users




_______________________________________________
Users mailing list
[hidden email]
http://lists.opensips.org/cgi-bin/mailman/listinfo/users