Which of the following should the administrator run on the server to verify routing functionality?

A Linux server is configured as a router, but the administrator notices that packets are no longer being routed. Which of the following should the administrator run on the server to verify routing functionality?

A.
cat /proc/self/status

B.
/etc/rc.d/network status

C.
/etc/rc.d/squid status

D.
cat /proc/sys/net/ipv4/ip_forward