On Thu, Jul 22, 2004 at 10:39:05AM +1000, Peter Hardy wrote:
> On 07/22/04 10:18, Mary Gardiner wrote:
> > b) set up a second server on a different IP address and update the
> > nameservers. (Not all clients will notice immediately because DNS can
> > be cached.)
> 
> It's probably worth pointing out that it's not uncommon for DNS servers 
> to have fairly long caching periods. My domains usually have a TTL (time 
> to live) of 24-48 hours. This is because DNS records are mostly static.
> 
> I've seen hosting providers set TTLs of a week, which seems to me a 
> fairly underhanded attempt to minimise churn.

When you're planning on moving, get the DNS moved to your cooperative
provider first.  You don't even have to tell the hosting provider your doing
it, unless you've foolishly got the domain registered in their name.  Just
get the registry key for the domain, throw the domain on some new (short
TTL) DNS servers, and then tell the registrar to delegate to your new
servers (which, at first, just carry a copy of the DNS data as provided by
your hosting provider's DNS, but with a very short TTL).  When you've got
your new website at the new host ready, just change the DNS over.  Give it a
few days, and then cancel the contract with your old hosting provider.

It's still going to take time to do, but I wouldn't particularly want to
rush those sorts of things even if the old provider had 60 second TTLs. 
It's also tricky if you've got live databases and whatnot at the provider,
but a few hours of "this site is currently under maintenance, please go
away" in the wee hours while you move the dynamic data around shouldn't be
too much of a killer, unless you're big -- in which case, there are other
(costlier) ways to solve the problem.

- Matt
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