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T28P (and probably others) does not send DNS request after TTL timeout - Printable Version

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T28P (and probably others) does not send DNS request after TTL timeout - dnk2012 - 07-31-2013 01:21 AM

Yealink phones have a firmware bug. We have tested this on the model T28P phone, but believe it to occur in all yealink models.

When the phone does a DNS lookup it is ignoring the published "time to live" value. When the DNS lookup expires, the phone is supposed to do another DNS lookup. Instead, the phone caches the value of the domain name, and continue to use the name past its expiration.

Further, if a phone tries to register to a domain, and no answer is received, it should do another DNS lookup immediately.

Please find that attached file, which shows that after 2 minutes of TTL, the phone did not send another DNS request.


RE: T28P (and probably others) does not send DNS request after TTL timeout - Yealink Support - 07-31-2013 03:30 PM

Hi DNK,
Please try our V71 beta firmware to check again:
ftp://yealinkftp:yealinkftp@ftp.yealink.com/00.Firmwares/T2x/2.71.0.125.rom
We added a DNS Cache feature, when the phone can’t get a result from DNS server, users can set a value in DNS Cache themselves.
Any test result please let us know, thanks.


RE: T28P (and probably others) does not send DNS request after TTL timeout - dnk2012 - 08-01-2013 03:52 AM

The bug was that the phone was not even trying to send a DNS request after the TTL value. Caching is used if the DNS server is not reachable.


RE: T28P (and probably others) does not send DNS request after TTL timeout - dnk2012 - 08-02-2013 03:09 AM

I loaded T28P with this firmware, and phone is sending DNS requests after TTL timeout. Thank you.


RE: T28P (and probably others) does not send DNS request after TTL timeout - dnk2012 - 08-08-2013 03:12 AM

What are the firmware versions of the following models that solved this problem ?
T18
T20
T22
T26
T28
T32
T38
T46
W52


RE: T28P (and probably others) does not send DNS request after TTL timeout - Yealink Support - 08-08-2013 01:45 PM

Hi DNK,
We will release our V71 commercial firmware this month, which resolved this issue, after that you can download the firmware from our website, is it OK?