Many ISP's have multiple DNS servers on their network (especially national or regional ISP's), so it couldn't hurt to email them or even call. However the addresses that you get on your computer when you sign on are usually the most local to you, and therefore the fastest for domain lookups. Of course, the Dreamcast won't often need to do lookups unless you're doing something like web browsing with it, so it may not make a big difference.
However it's somewhat odd to see a server address ending in 0. It is completely possible, just rare because the .0 address is often the network address and isn't usable in that case. Are you sure the address ends with 0? And what other setting isn't taking if you use .0 for the DNS server?
The_good_guy, what in the world are you saying to do? You can't just take any IP address in a traceroute and use it as a DNS server. Those are routers, not servers. Routers don't 'have a copy of your DNS' (I'm not even sure what that means).
Technically, we could just give him any DNS servers that we know of and he could use them, they just wouldn't be as fast as using his own ISP's servers.