[89445] in North American Network Operators' Group
Re: FW: DNS TTL adherence
daemon@ATHENA.MIT.EDU (Igor Gashinsky)
Fri Mar 17 05:43:33 2006
Date: Fri, 17 Mar 2006 05:43:02 -0500 (EST)
From: Igor Gashinsky <igor@gashinsky.net>
To: "Thurman, Steven" <steven.thurman@wamu.net>
Cc: nanog@merit.edu
In-Reply-To: <E73B77BE9ADCF44BB936593743E85ADD04EA3106@exmsea008.us.wamu.net>
Errors-To: owner-nanog@merit.edu
:: >So, if you, or the original poster, is going to move
:: ${important_resource}
:: >around ip-wise keep in mind that your ${important_thing} may have to
:: >answer to more than 1 ip address for a period much longer than your
:: tuned
:: >TTL :(
::
:: Thanks all for the responses. I do understand we may need to support the
:: old IP addresses for sometime. I was hoping someone had performed a
:: study out there to determine what a ratio maybe for us supporting an old
:: IP address (I know our traffic profile will be unique for us thus it
:: would only give us a general idea).
::
:: For example if we change ip addresses will we need to plan on 20%
:: traffic at old site on day1, 10% day2, 5%, day3, and so on...? There are
:: also issues related to proxy servers and browser caching that are
:: independent of DNS we will need to quantify to understand full risk. The
:: more data we have will drive some of our decisions.
In my not-so-scientific "studies" with changind IPs for a fairly large
volume site, I found that 90% of the people will use the new ip within an
hour of TTL expiration, 99.999% of the people within 3 days, and that
remaining .001% may take years....
As someone said earlier, some parts of the 'net are just broken beyond
your control...
-igor
