Fw: Switching Host

[Kevin Darcy]

Josh Knepfle wrote:

>----- Original Message ----- 
>From: "Barry Margolin" <barmar at alum.mit.edu>
>Newsgroups: comp.protocols.dns.bind
>To: <comp-protocols-dns-bind at isc.org>
>Sent: Thursday, July 08, 2004 8:22 PM
>Subject: Re: Switching Host
>
>
>  
>
>>In article <cckmg8$1pv5$1 at sf1.isc.org>,
>> "Josh Knepfle" <josh at sparkpeople.com> wrote:
>>
>>    
>>
>>>"Barry Margolin" <barmar at alum.mit.edu> wrote in message
>>>news:cci308$2hiu$1 at sf1.isc.org...
>>>      
>>>
>>>>What happens is that every time a server queries the old ISP's
>>>>        
>>>>
>servers,
>  
>
>>>>the response includes the domain's NS records in the Authority
>>>>        
>>>>
>section,
>  
>
>>>>and these update the TTLs of those records.  As long as it queries the
>>>>old servers more often than the old TTL, the old NS records will never
>>>>expire from the cache, and the server will never have to go to the TLD
>>>>server to get new NS records.
>>>>        
>>>>
>>>So does this say that unless you have the cooperation of your "old" ISP,
>>>people are not going to be able to get to your servers at the new host?
>>>      
>>>
>Is
>  
>
>>>this a known issue with the whole system?
>>>      
>>>
>>Yes, this is a longstanding problem that frequently bites people when
>>they switch DNS providers.
>>
>>    
>>
>
>Just out of curiosity, is there any talk of changing the procedure?  It
>would seem that as long as everyone went to the TLD server after the TTL was
>expired, this would be resolved (which, it seems, at least some people do).
>Or, am I missing something???
>
I think you're missing the fact that the TTL on the NS records is never 
expiring. In order to "fix" this, you'd have to change not just a 
"procedure", but the whole logic of how DNS caching works, and the end 
result would be a diminishment of caching and significantly more traffic 
to the TLD servers. I can't imagine the TLD operators ever agreeing to 
such a change, especially when the syndrome can be prevented with a 
little advance planning and co-operation between ISPs/hosting-companies 
and their  client domainholders.

                                                                         
                                       - Kevin