On Wed, 15 Mar 2006, Simon Waters wrote:
This behavior is unfortunately not unique.
Alas what others peoples servers do, shouldn't be an issue for you.
Your
problem is they can be coerced into a DoS attack, not that the data is stale.
actually, dos-attack-aside, the interesting thing is that lots of people (original poster perhaps included) believe that TTL's are adhered to except in some marginal cases. I think Rodney's point is that they are not adhered to anywhere near as much as we would all like to believe :(
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. Thanks again, Steve