FW: DNS TTL adherence

Igor Gashinsky igor at gashinsky.net
Fri Mar 17 10:43:02 UTC 2006

:: >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...


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