Please Whitelist This Site? I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :) If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads. If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK. Thanks for your understanding! Sincerely, Charles Kozierok Author and Publisher, The TCP/IP Guide

NOTE: Using software to mass-download the site degrades the server and is prohibited. If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP Administration and Troubleshooting Utilities and Protocols

TCP/IP DNS Name Resolution and Information Lookup Utilities (nslookup, host and dig) 1 2 3 TCP/IP Network Status Utility (netstat)

Sample whois Output

Table 295 shows the sample output of the whois command on a FreeBSD UNIX machine (I have stripped out some of the preliminary general information and legal disclaimers to keep the table down to size).

In this case, the registrar of the domain “pcguide.com” is pairNIC, the DNS registry division of pair Networks, the company I have used for Web hosting for many years (since 1997, as you can see). This output is public information, and lets anyone who has an interest in pcguide.com, for whatever reason, determine that I own the domain and learn how to contact me. (That is obviously not my real phone number, of course.) It also tells them that pair Networks runs the name servers that contain domain information for my domain.

TCP/IP DNS Name Resolution and Information Lookup Utilities (nslookup, host and dig) 1 2 3 TCP/IP Network Status Utility (netstat)