Nameservers/ hosting change Continued

[rjwmotor]

This is a continuation of an old thread located here:
[webmasterworld.com...]

I switched the registrar info and have copied my site at another host. It seems to be up and working at the new spot but I had a couple of questions before I change the nameservers.

1) Once I change them, approximately how long does it take for it to propagate around the world?

2) any ideas on when the best time of the week to do this is or does it matter?

3) I know it's a sensitive issue but does anyone know how long it takes Google to reassign PR from the old site to the new? Does it happen as soon as the nameservers are propagated?

Thanks in advance!

[jdMorgan]

1) Once I change them, approximately how long does it take for it to propagate around the world?
New systems are in place that can update in as little as four hours. But it may take up to two days, and some ISP's DNS caches may be broken and take even longer. I use 7 days as a minimum time to keep the old site up in parallel with the new. This is longer than necessary most of the time, which is better than shorter than necessary some of the time.

2) any ideas on when the best time of the week to do this is or does it matter?
It doesn't matter as long as the site exists on both servers while the DNS change is propagating.

3) I know it's a sensitive issue but does anyone know how long it takes Google to reassign PR from the old site to the new? Does it happen as soon as the nameservers are propagated?
There is no PR involved. PR belongs to a URL, not a site, not a server, not an IP address. A URL keeps its PR no matter where it is hosted.

Jim

[jtara]

Once I change them, approximately how long does it take for it to propagate around the world?

Maximum - TTL. Average, TTL/2.

TTL = the minimum of the "time to live" values from your SOA (Start of Authority) record and A (address) record. This is (or SHOULD BE!) under YOUR control, and isn't standardized, so nobody can say how long it will take YOUR change to propagate. Most sites, though, typically set a TTL of 1-2 days.

Resolvers and name servers that have cached your DNS information are REQUIRED to refresh their data once the TTL expires. Sometimes they don't, but that's entirely beyond your control.

The best way to effect a change is to first change the TTL to a smaller value. Once the old TTL has expired, make the change, wait for the new, smaller TTL to expire, then kick it back up.

You could set the TTL as low as, say, 5 minutes, and have it very quickly done with once you make the change.