Refer to the exhibit. A distributed DoS attack has been detected. The attack appears to have
sources from many hosts in network X/24. An operator in the network operation center is notified
of this attack and must take preventive action. To block all offending traffic, the network operator
announces a BGP route, with the next-hop attribute of 172.31.1.1, for the X/24 network of the
attacker.
Which two methods do the routers at the regional office, branch office, and telecommuter location
use to prevent traffic going to and from the attacker? (Choose two.)

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

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

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

D.
strictuRPF

E.
a route map to tag all traffic from the X/24 network with the no-export communityattribute