The tools help facilitate common system administration tasks.
Network ToolsNSLookup Gateway - Queries 10 major US nameservers and several foreign nameservers.
Custom NSLookup Gateway - Do your own lookup off of the DNS server that you want.
MXLookup Gateway - Same as above, but it looks up the MX (Mail Exchanger) for hosts.
Whois Lookup - Checks domain to see if its registered. And if so, it provides info on it.
Traceroute Tool - Traces the route to said host and sends 10 packets and reports the results.
Long(er) Traceroute Tool - Traces the route to said host and sends 50 packets and reports the results.
Other Network ToolsMX Toolbox's Realtime Blackhole Lists (RBL) checker
MX Toolbox's Open Relay Tester