ENUM DNS Cache?

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Baguk
Posts: 14
Joined: Thu Aug 13, 2009 9:30 am

ENUM DNS Cache?

Post by Baguk » Mon Nov 21, 2011 1:55 pm

Dear Aaron, All,

I have an issue with using ENUM of e164.org. Sometimes one of my DIDs resolved to old SIP address. This happens not always, but only time to time.

Please let me explain it step-by-step:

1. I have a did 123123123456
2. This DID has been registered on e164.org with SIP a@sipsorcery.com and has been successfully verified.
3. After verification DNS entry of e164.org has been updated to b@sipsorcery.com.
4. Lookup on Sipbroker ENUM respond correct value.

Issue: sometimes (not always) sipsorcery enum lookup returns the old sip (a@sipsorcery.com) when looking for 123123123456, instead of actual one (b@sipsorcery.com). Both nslookup and sipbroker's lookups returns anytime correct one (b@sipsorcery.com).

Aaron, has siprocery somewhere ENUM/DNS cache? Is it possible to "update"/"flush" it anyhow?

Aaron
Site Admin
Posts: 4652
Joined: Thu Jul 12, 2007 12:13 am

Re: ENUM DNS Cache?

Post by Aaron » Tue Nov 22, 2011 10:16 am

Baguk wrote:Aaron, has siprocery somewhere ENUM/DNS cache? Is it possible to "update"/"flush" it anyhow?
Nope the sipsorcery ENUM lookups aren't cached. Each lookup sends a fresh DNS request. I guess it's possible the upstream DNS server could cache the records but with ENUM records, which are NAPTR records, they specify a time to live and I'd be pretty confident the DNS server sipsorcery uses is respecting that.

If the old address appears from time-to-time over a period of days then I'd say it's actually an issue at the source DNS set up. The primary server is probably correct and one of the secondary servers could be out of date.

Baguk
Posts: 14
Joined: Thu Aug 13, 2009 9:30 am

Re: ENUM DNS Cache?

Post by Baguk » Tue Nov 22, 2011 7:55 pm

Hello Aaron,

Thanks a lot for your answer. It seems that the issue was (is) caused by e164.org and neither sipsorcery nor dns in general. Duing intensive "F5" (refresh) on sibroker enum lookup I saw also sometimes old sip address as responce. Than I re-added DNS record on e164.org and now seems DNS response from e164.org to be correct.

Thank you again!

Baguk
Posts: 14
Joined: Thu Aug 13, 2009 9:30 am

Re: ENUM DNS Cache?

Post by Baguk » Thu Dec 01, 2011 1:40 pm

Hello Aaron,

As this issue occurs also with other my numbers, I did a small research. Results of my findings are:

There are few DNS servers serving e164.org subdomains. One of them, ns.e164.biz (64.34.96.238) returns all NAPTR records, which were added and then deleted using e164.org web-interface. Said other words, any modification on e164.org on particular "number" are just added to this NS as new entry, but not as update to previous entries. I hardly believe it related to my domains only and almost sure other people changed their NAPTR on e164.org experiencing same issues.

I addressed this bug to e164.org, but not sure it will be fixed shortly. Aaron, is it possible to address ENUM by sipsorcery to particular DNS server, to avoid usage of na.e164.biz for e164.org subdomains?

Aaron
Site Admin
Posts: 4652
Joined: Thu Jul 12, 2007 12:13 am

Re: ENUM DNS Cache?

Post by Aaron » Fri Dec 02, 2011 11:11 pm

Baguk wrote:I addressed this bug to e164.org, but not sure it will be fixed shortly. Aaron, is it possible to address ENUM by sipsorcery to particular DNS server, to avoid usage of na.e164.biz for e164.org subdomains?
Not very easily. When the ENUM lookup, which is just the same as any other NAPTR DNS lookup, is required the sipsorcery servers send the request to the DNS servers that have been set at the operating system level. Those DNS servers are the ones supplied by the hosting company where the sipsorcery servers are housed. Once the request gets to one of those DNS servers then it will make a choice about which of the e164.org name servers to use. It would be possible to implement a mechanism to do an ENUM lookup on a specific DNS server but it would mean re-inventing the wheel to a certain extent.

Hopefully the issue will be fixed by the admins of the faulty DNS server.

Apart from that has ENUM ever helped you much apart from lookups on your own numbers? It appears to me that the whole ENUM idea has well and truly lost momentum and where once national telecoms bodies were running trial services they are now all closing or winding down. In some cases that happened when they realised there was no money to be made attempting to charge end users to maintain their ENUM entries which was always a stupid idea.

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