"Document Contains no Data" or "A DNS error has occurred"

When I run a search on any RTK NET database using Microsoft Internet Explorer as my web browser, I get an error stating that there was a DNS error and that I should attempt to refresh the page (which I did quite a few times). When using Netscape Communicator 4.6, I receive an error stating that "the document contains no data." Is your server down? Am I able to retrieve data using these versions of web browsers?

What is the problem?
RTK NET database searches will fail if the numeric internet address of a caller's computer is unlisted, incorrect, or cannot be verified. This failure -- known as a "reverse DNS lookup" failure -- is not in the caller's computer nor ours. It rather occurs in a separate computer -- a domain nameserver (DNS) computer typically operated by the caller's internet service provider. That computer lacks a proper address listing for the caller's computer.

Why do reverse DNS lookup failures occur?
Every Internet computer has a numeric "internet protocol" (IP) address which uniquely identifies that computer in the world-wide Internet. There is also a DNS computer officially assigned for every block of IP numbers, whose job is to translate those IP numbers into hostnames and back again.

IP addresses (which look like 123.456.789.012) can be assigned to a caller's workstation permanently or just for the duration of an internet session -- such as the home computer of an AOL user. Either type of IP address will work fine on RTK NET -- so long as the caller's IP number can be verified (from its DNS computer) when the call is received.

When somebody calls our database computer, the calling computer puts its IP number in the call. Our computer asks the official DNS computer to verify that IP number, through a process known as "reverse dns lookup": Our computer asks the DNS computer for the "hostname"associated with the calling IP number and for the IP address associated with that name.

If the DNS computer sends back answers that don't match (or no answer), our computer doesn't know where to send the caller's database search results!

And when a caller's computer receives no response from ours, some web browsers report it as "document contains no data" or "remote server error." Most likely such reports just mean that the caller's pc/workstation has an unlisted IP address -- hidden behind a company "firewall" or behind a DNS computer which has no IP address listing for the workstation.

How to fix the problem
Callers experiencing reverse DNS lookup failures have two options: either to "unhide" their workstation's IP address -- by adding it to the DNS computer's address list -- or to call from (different) workstation whose IP address will be verified by its official DNS computer.

Most callers cannot on their own add IP numbers to the official DNS computer address lists, nor can we. That change must be made by the DNS computer operator, typically the callers' internet service provider or technical support personnel at a workplace. Callers should ask them to enable "reverse DNS lookups" for their workstations.