which command will help locate the problem?

If you suspect that a gateway machine on your network has failed but you are unsure which machine, which command will help locate the problem?

A.
ps

B.
netstat

C.
nslookup

D.
ifconfig

E.
traceroute

Explanation:
A) lists processes
B) lists open ports
C) lists DNS entries
D) lists information about ethernet adaptors

traceroute has to be installed separately (at least in ubuntu)