What're primary DNS suffixes and connection-specific DNS suffixes?

[chrstrbrts]

Hello,

If I call ipconfig /all in command prompt or Powershell, all my enabled network adapters pop up.

Though, at the top is a windows ip configuration listing.

Under it, there are listings primary DNS suffix and a DNS suffix search list.

What are these?

I know that DNS is a server that takes in an English domain name and yields a binary IP address.

But what are these suffixes?

Also, under a specific adapter I find connection-specific DNS suffix.

What is this?

 

[razel]

Are you sure it's suffix and not server? I don't even see DNS suffix listed in mine. Other time I've seen DNS suffix is on a computer at work.

 

[Gryz]

Nobody uses that anymore. I doubt anyone here knows what it is. Forget it.

 

[chrstrbrts]

Nobody uses that anymore. I doubt anyone here knows what it is. Forget it.

Humor me. What is it?

 

[Gryz]

The suffix is the part of the domain-name that is pasted behind the hostname.
Suppose you have a machine with a FQDN "monkey.cs.someuni.edu".
If you want to telnet/ssh to that machine, you have to type that whole name every time.
But if you set the suffix searchlist to "cs.someuni.edu", then you can just type "ssh monkey".

You can play games with this. E.g. you can set the searchlist to "cs.someuni.edu, someuni.edu".
Now you still can type "ssh monkey" to connect to your machine in the CS department.
But suppose there's a machine called "elephant" in the chemistry department.
The chemistry department has sub-domain "ch.someuni.edu".
Now you can connect to that machine by typing "ssh elephant.ch".
The suffix-searchlist tries: "elephant.ch.cs.someuni.edu" which fails.
And then tries "elephant.ch.someuni.edu" which will yield a DNS-record.
And then the ssh succeeds.

Got the idea ?
In the past, when I was a Unix sysadmin, we used this in a way similar to my examples.
Nowadays, people are to stupid to understand a simple system like this, so nobody uses it to its full capabilities.
It can be quite convenient.

At my last job, in a multinational with 100k employees, the internal machines didn't even have DNS-names. You had to type ip-addresses. Really sad.

 

[chrstrbrts]

So, a connection-specific DNS suffix only pertains to that specific adapter?

 

[chrstrbrts]

Also, my system has DNS suffix search list listed as home. What does that mean?

 

[dave_the_nerd]

So, a connection-specific DNS suffix only pertains to that specific adapter?

No, it's for the system as a whole. The system will try to resolve an IP for the hostname, and then connect to that IP with the appropriate adapter. (Based on the network IDs and routes stored in the routing table.)

Also, my system has DNS suffix search list listed as home. What does that mean?

It means that if you try to connect to "myprinter" your computer will contact your DNS server and ask for an IP address for either "myprinter" or "myprinter.home" before it gives up.

.home is a very common private TLD.

 

[mv2devnull]

As "home"?

Gryz did mention searchlist. Yours contains one entry: "home". When you use a name, for example in url, the name has to be resolved to an IP address.

You type http://foo/
Your system queries the DNS server for name foo.home. If that name resolves, then you use the IP address.
If not, then system queries the DNS server for name foo. If that name resolves, then you use the IP address.

If no name resolves to an address, then you get an error message/failure.

Your home router acts as DHCP server. It has given your machine IP address, netmask, address of DNS server, address of default route, the searchlist, and possibly other config. For some reason the router has been configured to give suffix "home", even though I doubt it does any good for you.