Re: Change of IP routing

From: Cliff Kurtzman <moderator_at_o-a.com>
Date: Fri 10 Jan 2003 10:19:01 -0600

Ryan,

While this subject is a bit off topic, it gets into issues that
seem to often be a source of confusion, and which are important
to understanding how everything we do on the Internet really
works... so I'll attempt to address this inquiry with the hope
that I am able to adds some degree of clarity rather than add to
the confusion.

To talk about "Changing the IP routing of a domain" could mean a
number of different things... because the language you are using is
not precise, it could be causing you difficulty in determining how to
make the correct change. Perhaps it would be useful to try to
provide a (rather simplified) overview of how domain registration and
DNS (domain name service) work.

When you register a domain with a domain registrar (such as
register.com, namebargain.com, verisign/network solutions,
godaddy.com, etc.) you list a series of nameservers (at least two).
In some cases, your registrar will offer to provide name service for
your domain, but in other cases you will choose to have your name
service provided elsewhere. For your registration of raceclubs.com
at registrar.com, for example, the listed name servers are:

   NS.MOHAWKISP.NET 216.6.9.249
   NS2.MOHAWKISP.NET 216.6.9.250

(You can find this information by doing a "WHOIS" search on your
domain at: http://www.networksolutions.com/cgi-bin/whois/whois )

Now when someone tries to send an email to raceclubs.com, or pull up
a web page under the racecars.com domain, their computer consults its
local name server to find out where to get the necessary information
to fulfill that request. The name server (through a process that
chains back to a root name server) then indicates that the
information that is needed to fulfill the request can be found at
either NS.MOHAWKISP.NET (216.6.9.249) or NS2.MOHAWKISP.NET
(216.6.9.250).

The indicated DNS (in this case NS.MOHAWKISP.NET or NS2) is then
consulted. If the request is for a web page, then a part of the
DNS called the "A Records" are consulted. The A records provide
instructions for the routing of web page request. There may be
multiple A records, because, for example, requests to www.racecars.com may
need to go to a different server than requests to corporate.racecars.com.
In the actual case of racecars.com, the DNS has only one A record, which
points to the IP address 66.212.227.140.

How do I know this? You can easily query any DNS on the net to see
the records within it using a tool called Dig. There is a web
interface to Dig at:
http://us.mirror.menandmice.com/cgi-bin/DoDig

Email is handled differently than web requests. When an email is
sent, the MX records within the DNS are consulted for routing
information. Again, there can be more than one MX record, as email
to someone @racecars.com may need to be handled differently than
email to someone @corporate.racecars.com. In this case, the MX
record for racecars.com points to mail.racecars.com, and then another
record specifies that mail.racecars.com corresponds to the IP address
196.14.236.206. The server mail.racecars.com will then provide
information on how to route the email for each of the users of
racecars.com... different users may have mailboxes at different
locations with different IP addresses.

So it boils down to this... if by "changing the routing of your IP
address" you mean that you need to change the IP address of the name
server that provides routing for your domain, then namebargain.com
should have some facility for you to revise the locations of your
name servers/DNS... look for it under that terminology.

On the other hand, if you want to change the server that web requests
or email requests are routed too, then you need to go to whomever
manages your DNS and have them make the change for you.

Finally, if you only want to change the IP routing of a specific
mailbox within your domain... then that request needs to go to
whomever maintains the mailserver that the MX record within your DNS
points to.

I presently use godaddy.com for the domain registrations of my
domains and those of my clients. I find their rates reasonable and
their interface simple, flexible, and fast. I also use godaddy.com
for email routing on some of my domains, which is a separate service.

I use a site called dnsmadeeasy.com to provide domain name service
for my domains and those of my clients. This is a great service with
a good web interface that removes a lot of the complication from
maintaining DNS. They also provide secondary name servers on
different backbones of the Internet, which is very important. For
additional redundancy, I will also sometimes use the name servers at
secondary.com.

The two name servers for racecars.com, at NS.MOHAWKISP.NET
(216.6.9.249) and NS2.MOHAWKISP.NET (216.6.9.250) are both on the
same Internet connection, which carries a great deal of risk. If
mohawkisp.net should lose its Internet connection, then your domain
is dead in the water. I have found that it is safest to have name
service provided on name servers on at least two separate
connections, and these connections should also be separate from the
connection on which you host your web site or mail server. This
provides the greatest redundancy along with the flexibility to
recover should some component of your system go down and you find
that you need to reconfigure your systems.



--Cliff

Clifford R. Kurtzman, Ph.D.
Moderator
Online Advertising Discussion List
http://www.o-a.com/
281-480-6300





Received on Fri Jan 10 2003 - 10:19:01 CST