Chief Delphi - usfirst.org down? Nope.

Quote:

Originally Posted by billbo911 (Post 792410)

Any changes to the DNS would be done outside of FIRST. It is quite often at the ISP level. Someone with a more specific knowledge of the workings of ISP's and the Internet may be able to give more details, HINT, HINT.

If you'd like a quick breakdown, here is how it works (being an ISP I do this stuff all the time).

Step one is the Registrar - think of registrars as a collection of entities that keep the main card catalog of the internet. They are the ones responsible for reserving a particular domain name for a company. Once you've reserved a domain name with a registrar, no one else should be able to buy that name and use it. If you have reserved a name it goes into the main catalog and no one else can have it. There is some registration information on the card, and a space to enter DNS servers.

Step two (performed on the Registrar's website) is to set the DNS server (Domain Name Server) names. Usually you have more than one of these for redundancy's sake in case one goes down it will use the other. This is like if you pulled the card out of the catalog to find out where to look for the actual sites or services associated with that domain name. When you type in your browser a domain name (www.usfirst.org) the first thing that happens is it finds the domain in the registrar database and looks up where the DNS servers are.

Step three is to set up various records on the DNS server. Sometimes DNS is maintained by the registrar, or it could be maintained by the ISP or even the end user. Each record on the DNS server has a very specific format, but basically it defines the alias to be used (say www.usfirst.org, or no alias usfirst.org), what kind of service you're providing (name lookup, Mail Exchange record etc) and an IP address. So for instance if the ip address of your main web server was 10.0.0.1 your "A" record for the web server would be:

www A 10.0.0.1

This means add WWW. to the beginning of the main domain name, and if someone is looking for that particular name within the domain return to the browser the address 10.0.0.1 to lookup the address. (BTW 10.0.0.1 is only valid as a local address).

If you have an FTP Server at 10.0.0.2 it might be:

ftp A 10.0.0.2

You can also have an alias. So if you wanted MYFTP.usfirst.org to point to the same address as ftp you could use:

MYFTP CNAME ftp.usfirst.org

Probably what happened is that that WWW A record got misdirected, but the main record for the host did not. This sounds like a change at the DNS level (rather than a registrar level which would redirect ALL the DNS to a new dns server name). Someone may have fumblefingered the IP address entry or left out the www CNAME or A record.

When you type www.usfirst.org into the browser your computer checks the registry, looks up the alias in the dns server, and returns an ip address to your browser, which proceeds to request the data you originally asked for from the server at that IP address. It actually queries a local DNS server, which has a copy of your IP address. If that copy is too old (set by the DNS timeout) the server will request a fresh copy from the root server, if not it will provide the cached copy. There is a serial number which is incremented each time the DNS record changes so it knows whether to refresh the local copy or not.

In any case while this information is maintained at the ISP or Registrar it should only be being changed if are actually changing something like the location of a server.

Hope that wasn't more information than you asked for and helped with an understanding of the DNS issues that may have happened.