Problem with domain name / DNS

Howdy everyone,

Little bit of panic mode here: updated a DNS server yesterday and things seem to be going out on us. We've registered the domain name with Yahoo, and their interface is a bit different from what I used to.

Anyway, it seems we've had the Yahoo default for our name server. Things were working but we had Email problems (solved through other means). I changed the DNS to that of our host since. At least I think... this is the problem.

Right now whois is showing us with 4 name servers: first two are our hosts, and the other two are Yahoo's, just in case. One of the two internet providers cannot get through to us.

Could I be wrong that our name servers were set to Yahoo's default? I mean, DNS is just an address book, right? We should be able to use anyone's?

You need to use the DNS provided by your host, so that people visiting your domain name will be served your web page.

That is what I changed it too, and it seems to have broken it... I was just worried that other internet providers would stop working too but it sounds like I did the right thing to get the broken one working.

Also, Yahoo asks for all sorts of IP addresses, for domain.com, http://www.domain.com, ftp.domain.com, etc (no NS), and I thought maybe this is why it was working with the Yahoo default for the DNS servers?