North American Network Operators Group
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Re: DNS TTL adherence

  • From: Joe Maimon
  • Date: Tue Mar 14 21:34:11 2006 

[email protected] wrote:
Although you asked for DNS servers - it helps to remember that no matter what the servers and resolvers do - IE will bring that behaviour to naught in many cases

http://support.microsoft.com/default.aspx?scid=KB;en-us;263558


*/"Thurman, Steven" <[email protected]>/* wrote:

Does anyone know if there is a research paper or statistics related
to what percentage of DNS servers do not adhere to advertised TTL
’ s? I am looking for some verifiable research on this topic if it
is available.
Thanks,

Steve


And the dnscache resolver cache service in win2k and up.


http://support.microsoft.com/kb/318803/en-us
http://support.microsoft.com/kb/245437/EN-US/

If you are expecting hot cutovers to anything by utilizing DNS, sure seems that you need to expect to support traffic to the values of the old records for some time.

And if you are expecting very long TTL's to give you extra insurance for outages and what-nots, expect spotty effectiveness.