Migrating to a NEW ISP -- PLEASE HELP ....

[Carl Brock Sides]

* mdtran at acton.com <mdtran at acton.com> [000717 11:32]:

> Our comapany is planning to migrate to MCI.
> We currently have the following services
> running on our network: smtp,dns,httpd.
> With this migration we will be given a new
> block of IP addresses.
> 
> We currently maintain our own primary dns server.
> We would like to make his transitions as smooth as
> possible.  If any kind soul out there has done
> this before, we would really appreciate any
> info/comments/etc ...

This is what I did, and it went very smoothly, maybe 10 minutes without
DNS. (I can't say the same for certain other services, but DNS went
well.)

(1) Registered new hosts with my registrar, with the addresses that your
name servers were to be on the new network. I.e. I had

ns1.towery.com          207.15.173.11
ns2.towery.com          207.15.173.12
ns3.towery.com          208.16.202.11
ns4.towery.com          208.16.202.12

Where 207.15.173/24 was the old network, and 208.16.202/24 was the new
one.

(2) Updated all thirty-something domains we controlled to list all four
of the nameservers: two that work, and two that don't. Don't forget to
update the NS rr's in your zone files as well. 

(3) The day before the transition, set the TTLs in all my zone files to
10 minutes.

(4) When the transition was made and new zone files were in place, ns1
and ns2 dropped off the internet, and ns3 and ns4 took their place. It 
took about 10 minutes for the rest of the internet to start resolving to
the new network.

(5) Reset my TTL to something reasonable, and changed ns1 and ns2 to
something on the new network. (I set them up as alternate IPs on
the same machines as ns3/ns4, i.e. ns1/ns3 are two different IPs on
the same interface of the master nameserver, and ns2/ns4 the same way on
the second. I'm not sure this is the ideal situation, but it hasn't
created any problems. I think at worst it would make things a little
slower if one machine were down if the remote nameserver tried ns1 then
ns3, before trying the working ns2.)

Of course, I was running both primary and secondary servers, with no
backup at the ISP. You may want to ditch any backup you have at your
current ISP, as they will probably just get in the way during the transition. 

-- 
Brock Sides
csides at autozone.com