Yes updating the default value will do.
Also here's what I do when I migrate servers.
1) Make the new server a clone of my old
2) Set the
www.domain.com to point to the new server
3) Set a rewrite rule on the new server to point to domain.com
4) Wait 48 hours
5) Shutdown the site
6) Migrate databases over
7) Turn the rewrite off
8) Set a rewrite rule on the old server to point domain.com to
www.domain.com
9) Switch the site back on
10) Point the
www.domain.com to the new server
11) Wait 48 hours
12) Shutdown the old server.
There hardly any down time (just the time to migrate the database).
TTLs are rarely used properly by ISPs they tend to cache for up to 48 hours.