DynDNS Wide Area Bonjour Support Goes Beta

Last week DynDNS released its beta support for Wide Area Bonjour and DNS Service Discovery. This means that if you own your own domain name, and you have a Custom DNS service with DynDNS, you can configure your Apple (s aapl) AirPort device (AirPort Extreme, AirPort Express and Time Capsule) to present itself as part of that domain, automatically updating your domain name and broadcasting configured services.

What is Wide Area Bonjour?

Wide Area Bonjour enables the same zero-config automatic service discovery functionality over the public Internet that we all enjoy on our local network (seeing our shared files, printers, scanners and so forth). If you have a MobileMe account and utilize the Back To My Mac functionality, you’re already using Wide Area Bonjour without even knowing it.

Why would we use this?

Most of us who use DynDNS use it to be able to let the IP Address that our ISP give us resolve with a friendly domain name (such as This basic free DynDNS service works really well as long as you have a third-party router that supports DynDNS (which most of them do). Unfortunately Apple, being Apple, does not support DynDNS in its routers, leaving you to run the OS X DynDNS updater application on your computer. The downside to this is that if your computer is asleep and your home Internet connection drops and reconnects (giving you a new IP address) DynDNS does not get updated until the computer wakes up. When wanting to use Snow Leopard’s Wake On Demand feature this is a problem, so this has meant “tough luck,” requiring you to run the DynDNS Mac client on multiple machines and hope the IP updating occurs often enough. It generally works fine, with the occasional expected downtime when your home IP changes at midday if computers are sleeping.

Does it work?

This DynDNS Community post explains the current problem the DynDNS team are having. The gist is that while the Wide Area Bonjour service discovery works just fine, the domain name IP allocation will only work if your IP does not resolve a reverse name lookup. This is an issue since almost all Internet Providers that give you a dynamic IP address have a full domain name allocated already. For instance, if you do a reserve name lookup on your dynamic IP you may get a name of This is a problem because of the way Apple’s Global Dynamic Hostname configuration currently works. It will only attempt to configure a name for the IP address if a name doesn’t already exist. DynDNS has queried Apple about the way this works and it appears to be non-intentional behaviour caused by a bug. Apple has indicated on the bonjour mailing list that a fix will come some time in the future, but at this stage there is no ETA. Apple will have to issue firmware updates for the Airport devices to make this work as expected.

What is working fine at the moment is Wide Area Bonjour service discovery. So if you have a static IP that does not resolve with a reverse name lookup and would like to emulate the kind of automatic service discovery functionality that you experience with Back To My Mac, you can achieve this goal with DynDNS now. DynDNS have two guides to assist with the appropriate configurations if you want to give it a try: