In news:b1991036-a4d3-4e80-b089-cfdacf3bdf89[ at ]l39g2000yqn.googlegroups.com,
mmccaws2 <mmccaws[ at ]comcast.net> requesting assistance, typed the following:
[Quoted Text] > Hi
>
> just finding some curious things that I'm trying to resolve the answer
> to. Here it goes.
>
> TTL for google is 5 mins
> I ping it then
> I show 'ipconfig /displaydns'
> it show that it has jus a couple hundred seconds left.
>
>
> Record Name . . . . . : google.com
> Record Type . . . . . : 1
> Time To Live . . . . : 205
> Data Length . . . . . : 4
> Section . . . . . . . : Answer
> A (Host) Record . . . : 209.85.171.99
>
> when i ping seattle.gov
> and I show ipconfig /displaydns
>
> seattle.gov
> ----------------------------------------
> Record Name . . . . . : seattle.gov
> Record Type . . . . . : 1
> Time To Live . . . . : 4066
> Data Length . . . . . : 4
> Section . . . . . . . : Answer
> A (Host) Record . . . : 156.74.250.21
>
>
> The amount of time to live is much less than 7200 seconds.
>
> Now I had flushed dns on my desktop when I started these queries, so
> all this info is new. Seattle.gov is not my parent domain so it would
> have no reason to be in my cache due to my desktop settings. So the
> question is -- Since the value is not 7200 seconds minus some short
> duration by the delay of ping and typing the next command, is the 4066
> reflecting the name server's time left on it's cache???? or how does
> that work?
>
> the soa says ttl is 2 hours. The captured response using Wireshark
> says the ttl is 1 hour. I get the impression that the servers my
> laptop is querying may have a maximum cache limit of 1 hour.
> Otherwise if the value is less than 1 hour it goes by the value. Is
> this posssible for Windows 2003 server DNS cache. What is the default
> cache value?
>
>
> thanks
> Mike
When you ping an FQDN, the local cache, as well as the DNS server that
served you the result, will keep it in cache until it's TTL expires. The TTL
is based on the record's TTL when it was created at the SOA, or the server
that is responsible for that domain name. Matter of fact, if you arrow up
each time you do an ipconfig /display dns, you can sea it counting down.
If you are using your own DNS server that resolved the record using
recursion, same with each time you look at it in your DNS server's cache
(with advanced view enabled). Each time you close and re-open the record's
properties, you can see it count down.
This is default behavior and how it works. Otherwise, a record will live
forever, not to say some DNS admins out there will not put in a 65,000 year
TTL, which is ridiculous. Same reason why TCP/IP packets have TTLs.
Otherwise the packet will float around on your network for infinity or at
least until the routers are rebooted.
--
Ace
This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.
Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCT
Microsoft Certified Trainer
For urgent issues, you may want to contact Microsoft PSS directly.
Please check http://support.microsoft.com for regional support phone
numbers.
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