You work as a network operator for an IT company. You have just detected a distributed DoS
attack which appears to have sources from many hosts in network X/24. You must take preventive
action to block all offending traffic, so you announce a BGP route, with the next-hop attribute of
172.31.1.1, for the X/24 network of the attacker. Which two methods will be adopted by the routers
at the regional office, branch office, and telecommuter location to prevent traffic going to and from
the attacker? (Choose two.)

A.
a prefix list to block routing updates about the X/24 network

B.
a static route to 172.31.1.1/32, which points to a null interface

C.
a dynamic ACL entry to block any traffic that is sourced from the X/24 network

D.
strict uRPF