List of command line tools used by all network/system administrators:

ping

tracert

psping, tcpview, psexec, autoruns, sysmon (www.microsoft.com/sysinternals)

rpcping

telnet

pathping

fport (www.foundstone.com)

netstat

nslookup

dig   (part of bind package)

portqry

test-netconnection (powershell cmdlet only available for Win 8.1 or greater)