To: Dominick who wrote (361 ) 1/22/1998 9:31:00 AM From: Scott Pedigo Read Replies (1) | Respond to of 2120
Caveat.... your sites or vendors cannot require "reverse dns" (what ever that is?) Reverse DNS is looking up a domain name in a registry based on an Internet address, the reverse of what is usually done. Every machine connected to the Internet has to have a unique address, so that the destination of a packet is unambiguous. IP addresses consist of four bytes, and are often written in decimal separated by dots: example 100.255.0.40 A big problem is that we're running out of addresses now. Ethernet addresses consist of six bytes. Don't ask me to explain when and what for each is used, even I am confused. The domain name part of a URL like my_firm.com (the www.my_firm.com part) is registered by one of the institutions which administer the Internet, and the person or company registering the name is assigned an IP address. When a browser attempts to get a page, it needs the IP address to put into the packets (the address of where the packets requesting a page are to be sent). The server returning the page needs the IP address of where to respond, which the access provider normally supplies to your computer when you log on. A lookup of the domain name (www.my_firm.com) is performed to get the IP address. At various locations around the world there are servers on the Internet with copies of the registry which can be queried. People creating Web pages sometimes put in links to IP addresses rather than domain names. After all, they know what IP address their site has been assigned, and if they want a link to a page on their site, this should work. In a strange twist of fate, however, the browsers don't know what to do with these IP addresses, even though that is what they ultimately want. So they query a registry to get the domain name corresponding to the IP address. Of course afterwards they end up querying the registry again to get the IP address for the domain name. Obviously there is some additional routing information which is obtained with the latter query, but I don't know all the details. So if your browser encounters such a page - one with a link to an IP address rather than a domain name - then this cable operator is telling you that you won't be able to follow that link. Not to worry - this is uncommon. I only got an error message once, and when I complained to the site Webmaster, they registered the server and replaced the link.