[OpenSIPS-Users] DNS Cache module

Ben Newlin Ben.Newlin at genesys.com
Fri Dec 7 13:14:22 EST 2018


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 <bogdan at opensips.org>
Date: Friday, December 7, 2018 at 12:21 PM
To: OpenSIPS users mailling list <users at lists.opensips.org>, Ben Newlin <Ben.Newlin at genesys.com>
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 ?


Bogdan-Andrei Iancu

OpenSIPS Founder and Developer


OpenSIPS Summit 2019

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

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

Non-authoritative answer:
Name:  customer.domain.com
Name:  customer.domain.com
Name:  customer.domain.com

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

Ben Newlin


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