[FX.php List] [OFF] Question about DNS TTL (time-to-live)
bob at patin.com
Thu Oct 13 09:47:37 MDT 2011
So here are the results from a test I just ran:
I have a website up at http://www.bobpatin.com; it's on one of my web servers here.
The domain name's TTL has been set to 300 seconds for a long time, probably months or years. For sure it's been set to 300 since at least last Thursday.
I changed the DNS more than 5 minutes ago for this domain name, to an IP that I'll be moving to this weekend. If time-to-live is obeyed, it should've done a re-lookup of the IP after 5 minutes, but if you try that site, you'll still see it, because DNS still thinks that domain is at the old IP address.
Why is this? I thought that, if I've had TTL set to 300 seconds for over a week, it would re-lookup the IP address, but it's clearly not.
Any thoughts? I'm planning to cut over to my 4 new T1 lines this weekend, and would appreciate any insight.
Longterm Solutions LLC
bob at longtermsolutions.com
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Member of FileMaker Business Alliance and FileMaker TechNet
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On Oct 11, 2011, at 7:38 AM, Bob Patin wrote:
> On Oct 11, 2011, at 7:31 AM, Steve Winter wrote:
>> So about 9 days ago you set the TTL really low, but then never changed the IP addresses…?
> Well, here's what I saw:
> On the 5th or 6th, I changed all the domains' TTLs to 300 seconds.
> On the night of the 8th, I moved my network to the new IP block.
> On the 9th, which is 3-4 days after I'd changed all the TTLs, some of the domains took as long as 24 hours to pick up the changed IP.
>> Or did you change them for a period of time last weekend…? either way, if the TTL had been low for a couple of days, stayed low through an aborted change, and change back, and has remained low, then you're about as set as you can be ;-)
> Good; so I'm going to try this again on the 15th and keep my fingers crossed. A wrong subnet mask made the whole thing a complete mess…
> Bob Patin
> Longterm Solutions LLC
> bob at longtermsolutions.com
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