GURLS

This plugin will dynamically replace a URL (example: www.black.com) with an alternate URL (example: www.blue.com) based on front page group membership. More info here: http://northernlinks.ca/docs/GURLS_Manual.pdf
This
plugin will dynamically replace a URL (example: www.black.com ) with an alternate URL
(example: www.blue.com ) based on front page group
membership. Consider this example:
A
Moodle site has a grouping named “SWAP” and this grouping contains two groups:
Red Group and Blue Group. Using the GURLS filter, the admin creates a swap
instance for the URL www.black.com .  Within this instance, the Red Group is
associated with www.red.com and the Blue Group with www.blue.com .
This
means that when members of the Red Group come across any page that contains the
URL www.black.com , they will see their
alternative URL www.red.com . Accordingly, members of
the blue group will see www.blue.com . This plugins can be used
for different purposes, but it was originally created to serve large media
files from a server that is closest to the user. In the example illustrated
below, www.red.com could be a server in
Brazil and www.blue.com could be a server in
China.