Preferred DNS server: Router or ISP

I would start by making sure that the settings are the same on every computer (have to rule it out)... then on each machine, right click on the network interface settings and do properties, double click on IPv4, then advanced.

From here, I would click on the DNS tab and manualy add the server in the top list then select the option "Append these DNS suffixes (in order):" and choose something such as .local or .mynetwork then tick the bottom two options.

Restart all machines after making these changes and go to the command prompt and type ipconfig /renew followed by ipconfig /registerdns

Next, at the command prompt, type "Nslookup" and just try the name of one or two machines and see what happens.

If you are still getting no where, check DNS settings on the router, it sounds like it is not allowing other machines to register / is a caching DNS server for the internet ONLY, if it does work - cool.

If this doesn't help, you may be best off just using hosts files or using a different firmware - but, hopefully it has helped.

Edit - Also, Just thought - Remember to check that ICMP Echo is allowed on the Windows Firewall!

To answer your questions:

1. You can do that, by modifying the hosts file on every computer you're going to use to access your local server from, by adding the correspondence ip <-> domain-name. It can be a perfectly valid solution if you plan to access your server from your laptop, for instance.

2. What a DNS brings is a world-wide registration of this correspondence, so that you'll be able to access your local server from any computer without having to manually change your host file.

3. I don't really understand what you mean by that, and how you would "link the domain directly to your ip". What do you have in mind, technically, to do that? I think you could get a better understanding of the problem by reading how DNS work in general.