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Dynamic DNS for DHCP connections

Jun 29, 20042 mins

* Merging domain names and DHCP

Sometimes you find some interesting tidbits on the way to somewhere else.  And that’s exactly what happened recently when Steve – along with Larry Hettick, his co-author of Network World’s Convergence newsletter – were conducting some product testing.

In particular, Steve and Larry were testing out a Session Initiation Protocol (SIP)-enabled router designed for SOHO and branch-office use.  The router – an IX66 Internet Gate from Intertex, also performs as a SIP registrar.

But there’s a fundamental problem.  In order to have the Intertex unit act as a SIP registrar, it must be registered with a DNS service.  And under most circumstances, it’s tough to register a domain name when you don’t have a fixed IP address.  But the support people from Ingate, the sister company of Intertex, turned us on to a most interesting service.

The site offers free domain names that are compatible with Dynamic Host Configuration Protocol (DHCP).  You simply go to the site, and, if you’re willing to use one of its domains, you define what you would like as your personal domain name.  For instance, one of its domains is “”  So you might sign up for “”  Then, assuming you have a compatible router, every time the router gets a new IP address, it automatically updates the DNS.

While hobbyists and gamers will really like this function, it also has a business application, particularly for the smaller office environment.  Just as Steve and Larry are using this for registering SIP registrar services, this can be used any time a fixed domain name is used for a site that uses DHCP.

IPv6 will eventually solve the problem of insufficient IP addresses.  But we don’t see IPv6 becoming widespread any time soon.  So while we’re using DHCP for myriad reasons, this provides an excellent workaround.  By the way, for more commentary on the SIP testing, be sure to check out the Convergence newsletters, which are archived at