I. INTERNET TECHNOLOGY BACKGROUND INFORMATION

Basic or detailed Internet information and tools to find a router or an ISP anywhere in the world.

• HTTP protocol explained with several links to related web sites)
• 404 Research Lab (A very nice and complete lab to handle the 404 - page not found - error message)
• Understanding IP Addressing: Everything You Ever Wanted To Know (Very good but technical explanations)
• Need to know who belongs to a router/isp in the Asian, American or European region? Type in the I.P. number!
• The geography of the Internet
• The Internet Weather Report (animated maps of current Internet lag) with data since 1994
• A very large index traceroute web servers (200+)
• Mime Types
• List and explanations of HTTP status codes (such as not found [404] or forbidden [403])
• Dynamically Generating Customized Error Pages ("..This
  example shows how to display dynamically generated customized error pages and also demonstrates how to write customized error class Server Application Functions (SAFs)...")
• Mapping the Internet with Traceroute (Tracert) [An excellent tutorial!)
• Introduction to TCP/IP
• Creating Your Own Error Pages (Tutorial)
• About Port numbers
• The Public DNS FAQ
• and more...

II. INTERNET TOOLS

Many excellent tools (often online) to test the Internet connectivity and your connection.

• Traceroute, Lookup, Ping, HTTP Headers, E-mail relay Check, and WHOIS Tools
• Shows in real-time some ping statistics of ISP's.
• Enter a host to trace to or trace to yourself. It is a great tool to check connectivity from outside your place. You can even install MultiTrace in your browser, too! (but IE4.0 only)
• Various Internet & TCP/IP performance measurement tools. Impressive links. Some of the tools are free. Very technical contents.
• Online tool to find out important information on any web server in the world. Tells you the WebServer software, HTTP protocol version, default location, default site size, and more. It can even give you vital statistical information on your connection to that server
• Many Traceroute related tools & information. A comprehensive site with many links
• VisualRoute Server ("..provides a (live) graphical traceroute from an US server in Virginia to any other network device you choose. To trace back to your computer, just press the button with your IP address below. To trace to any other network device, enter the host name or URL.." - Nicely done!
• IP Address Tool
• Locate domain names based on their names
• Security Scan ("..The BlackCode Security Scan is an Online tool which makes an exhaustive test on your computer or firewall searching for open ports...")
• HTTP 2 Telnet gateway ("..This HTTP to TELNET gateway allows you to access any telnet connection from the WWW without the need for any special client software, except (currently) the support of frames..")
• Network tools: You can test here everything at once.
• Visual Route (Either from U.S. West coast (~Seattle) to own location or one entered. Very nice done)
• Test your relay ("..Unlike most other online testing tools we do perform full end to end testing by looking of the mail really goes through to the receiver and not just if it was accepted by the server..."
• How fast is your Internet connection? YourSpeed will measure how fast you can really surf. The measurement simulates normal surfing behavior by fetching images from a set of 40 popular web sites. The result is an easy to understand number that quantifies your speed (Nice design and an excellent test tool)
• and more...