Bonjour, sometimes referred to as zero-configuration networking, is a networking technology that allows devices to automatically discover each other without any configuration or network setup.
Some versions of the AirPort Extreme Base Station and all versions of the Time Capsule support using Bonjour to advertise services across the Internet. This requires using a Dynamic DNS hostname (or dynamic global hostname) and password you received from your Internet service provider (ISP) or network administrator.
By assigning your AirPort wireless device a dynamic global hostname, you can access the device outside the current local network, even if the public IP address changes at regular intervals.
After you have your account information, follow these instructions to enter the information into AirPort Utility.
Open AirPort Utility, located in the Utilities folder in the Applications folder on a Mac, and in Start > All Programs > AirPort on a Windows computer.
Select your device in the list, and then click Manual Setup. Enter the password if necessary.
Click Base Station or Time Capsule, and then click Edit next to the name field.
Select “Use dynamic global hostname,” and then enter the information for your account.
Check with your ISP or network administrator if you need more information about support for Bonjour.