Over time, I've noticed if I've entered the wrong domain (.gov, .com, .net) in a URL, the site is redirected to the correct site instantaneously . For example, www.usps.gov --> www.usps.com. Is this the browser, the site itself or something else causing the redirect?
There are many mechanisms that can cause this to happen. In this case it is the web server that is doing the redirect:
Your browser makes a connection to the webserver at www.usps.gov, which replies with a
Note that if you are using firefox, you can get it to tell you when a site is attempting to redirect in
For details on various methods, see http://en.wikipedia.org/wiki/URL_redirection (.htaccess, html redirect, server-side scripting, 301, etc) and http://en.wikipedia.org/wiki/CNAME_record (DNS redirect)