问题：

[多选] Which three of the statements below correctly describe the characteristics of Autonomous Systems in routed networks?（）

A . Within an AS, all routers must run either BGP or IBGP.
B . An AS uses exterior gatew ay protocols (EGPs) to exchange information with other autonomous systems.
C . An AS is a group of routers under the same technical administration.
D . Within an AS, routes learned through BGP can be redistributed using interior gateway protocols.
E . Wi thin an AS, routes learned through an interior protocol cannot be redistributed using BGP to other autonomous systems.