Hostname and User-Agent

Can this information be used to find out who I am?

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What is a Hostname?

Reverse DNS turns an IP address into a hostname -- for example, it might turn 192.0.2.25 into host.example.com. Reverse DNS (rDNS) is a method of resolving an IP address into a domain name, just as the domain name system (DNS) resolves domain names into associated IP addresses. One of the applications of reverse DNS is as a spam filter.

Because IP addresses are tedious to deal with and hard to remember, an IP address may also be assigned a host or domain name. You can think of an IP address as someone's physical street address and the host/domain as Bob's House. Multiple host/domain names can be directed to one IP address (as is often the case and referred to as virtual hosting). Host names may be looked up to find IP addresses, and visa-versa.

A hostname (occasionally also, a sitename) is the unique name by which a network attached device (which could consist of a computer, file server, network storage device, fax machine, copier, cable modem, etc. ) is known on a network. The hostname is used to identify a particular host in various forms of electronic communication such as E-mail or Usenet. Hostnames are used by various naming systems: NIS, DNS, SMB, etc.

What is a User-Agent?

A user agent is the client application used with a particular network protocol; the phrase is most commonly used in reference to those which access the World Wide Web. Web user agents range from web browsers to search engine crawlers ('spiders'), as well as mobile phones, screen readers and braille browsers used by people with disabilities.

When Internet users visit a web site, a text string is generally sent to identify the user agent to the server. This forms part of the HTTP request, prefixed with User-agent: or User-Agent: and typically includes information such as the application name, version, host operating system, and language. Bots, such as web crawlers, often also include a URL and/or e-mail address so that the webmaster can contact the operator of the bot.

Last Updated Monday, November 19 2007 @ 08:30 pm PST