Requirements for Software Update Service
Summary
OS X Server allows you to configure a local Software Update server so that workstations on your network can download and install Apple software updates from your local server instead of Apple's public Software Update service.
Products Affected
Lion Server, Mac OS X Server 10.4.x (PowerPC), Mac OS X Server 10.4.x (Universal), Mac OS X Server 10.5, Mac OS X Server 10.6, OS X Server (Mountain Lion)
Requirements for hosting a software update server
The Software Update service requires that the server is registered in DNS (Domain Naming Service) and resolves correctly. The DNS name of the server is used by the clients to download updates.
The synchronization module accesses the following public Software Update servers on destination port 80:
http://swscan.apple.com
http://swquery.apple.com
http://swdownload.apple.com
http://swcdn.apple.com
The latter (http://swcdn.apple.com) currently redirects to the Akamai content distribution network that hosts the updates. Note that the redirected IP address of http://swcdn.apple.com may vary over time or by geographic region.
Authenticated proxy servers are not supported by the synchronization module, which means updates will not be mirrored by the server. While the synchronization module may work with non-authenticated and transparent proxy servers, Apple recommends that the Software Update server have direct access to the public Software Update servers listed above.
- Dedicated network connection to the Internet
Software Update Server requires that the server have a dedicated connection to the Internet (specifically, to the URLs listed above in the "Servers and ports" section). If connectivity to the Internet is lost for more than 8 hours, Software Update Server will time out.
Read more http://support.apple.com/kb/HT3923