Date: Sat, 7 Feb 1998 10:53:23 EST From: who me? Subject: [WRITERS] FILLER: What DNS? Bad Netscape Communicator! Anitra wrote: :) You can occasionally get "No DNS" message when everything is up and :) running -- one of those roving potholes on the Information Highway :) just got in the way of the connection between your server and your :) target site. well, sort of, but not really... Let me explain a bit of the mystery of DNS... DNS is Distributed Name Service. Under Windows95, if you go to control panel, open up networking, click on your TCP/IP->dialup adapter, and click the properties, you'll find DNS configuration there. There are probably two or three numbers (18.70.0.160 for example) in there. These are your DNS servers... (oops--I assumed that you aren't connected via ethernet, you are dialing in. if you are connected differently, the information will be hiding in a slightly different place, but DNS is the same. please ignore this sidetrack...) So what does DNS do for you? Where you like to enter names (megara.mit.edu, or geocities.com), computers like these fun numbers. Long ago, we forced all hosts to have host tables locally for everyone they were likely to talk to. However, upkeep on this turned into a real pain. (Imagine having to tell every computer on the internet when one new one is added, one removed, or anything like that...a little like telling everyone in the U.S. when you move...) So someone said...suppose we had a service where all the hosts know is a few server addresses--and the servers keep track of the name/number stuff? Anytime the host wants to know where some name is, it can ask. (in the background, there is a whole lot of work going on...when your local DNS server doesn't recognize the name, it asks its friends...a bit like the local information asking a remote info operator about things) And that was the birth of DNS... When you get the error "No DNS Entry", your computer has asked a DNS server just who this megara.mit.edu is--and been told that he's a mystery. When life is good, this means you misentered the name or something like that, so there really isn't anyone answering to that name. However, when life is bad (aka the DNS servers are broken--which may mean they are unreachable, they have lost their minds, their friends aren't talking to them, or various other ills--normally they are fairly healthy beasts, but...), it is a lie. It does NOT mean your software has "gone bad" (software rarely rots). Frankly, I had consistent DNS problems one night recently, and MIT is careful to keep their DNS servers in good shape. Hearing that an ISP has some problem with their DNS servers doesn't surprise me--there are several hacker attacks dedicated to them. When you are doing the same thing that has worked consistently before, and you haven't made any major changes recently--and it doesn't work this time--don't leap to the conclusion that you are doing something wrong. There are a number of transient problems that can occurs on the internet (where transient may mean seconds or days, depending on the problem and the maintenance staff--although most problems are hours at most). It is a complex system, with a number of parts that have to work to connect hither and yon--not just your computer/software, but a whole flock of semi-invisible intermediaries. semi-invisible? well, when they are working correctly, you don't know they are there. when they are not doing so well, you are liable to get technobabble errors ("No DNS Entry") which aren't quite clear enough to show you what is wrong, but inspire widespread fear. tink