Use this tool for a detailed report. Online WhoIs Whois provides information on registered computer network users, domains, and organizations. Use this tool for a detailed report of 117 top level domains. Poster A great overview of the OSI model layers for different protocols. This yet another great poster that shows the different protocols per OSI layer.
Poster Shows how encapsulation is set up, shown per protocol.
Service A very detailed document on DDOS or denial of service attacks. An easy to read and extensive view on the OSI model and all layers. A list of all known port numbers with a short descriptions. A NSA guide to securing your NT system in multiple environments. The best hands-on security tips for Windows NT with great explanation with each tip.