Free Network Utilities & Research Tools
Utility Source Code
Whois Lookup.
Get Whois records automatically for domains worldwide.  Supports almost all TLDs.
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Domain Check.
See if a domain is available by checking both WhoIS and DNS databases.
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Ping.
See if a host is reachable by sending a ICMP packet to them and timing it.
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NsLookup - DNS Query.
Look up various domain (DNS) resource records with this version of the classic NsLookup utility.
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TCP/IP Port Query.
Grab a web page, look up a domain, and more.  Test certain ports on your machine to see if there is a response.
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Traceroute.
Trace the path from this web server to another server on the Internet somewhere.
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Traceroute with Analyze Path graph.
Do a simple, graphical traceroute showing time for each hop.
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Email Dossier.
Validate and investigate email addresses.  This utility will contact the remote mail server for a more thorough check.
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Browser Mirror.
See what your browser reveals to other parties whose websites you visit.
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