WSUS server connects to 'akamai' server?

To the best of my knowledge: Akamai provides download services to third parties,
including Microsoft. Both Windows Update and WSUS probably download content
from Akamai rather than directly from Microsoft. Akamai has servers in and/or
network links to many ISPs, and can figure out which ones are closest to you,
resulting in much higher download speeds.
(taken from http://forums.techarena.in/server-update-service/1125911.htm)

Akamai works by configuring DNS to resolve differently depending on geographic location (ping download.windowsupdate.com to see this in action).
(taken from www.netcrucible.com/blog/2003/09/29/akamai-or-backdoor/)