How do hostnames work on a LAN?

Question

On my LAN i can use a computers hostname instead of its IP address to refer to it, but how does this work? Nslookup doesnt work with the hostnames, so its not using DNS. Is it something to do with NetBIOS? However it works, is my router the central 'server' for the hostnames?

Answer 1

Every computer on the Lan will have a "computer name" these are indeed broadcast by NetBios (if enabled) and in the TCP headers and they are contactable by the computer name. If you have two computers with the same name.. they wont work correctly by name although will be reachable by IP!

Your router in this case is just a switch sending packets to the correct "destination" in fact you could even replace it with a switch and the systems would still work (if you put an IP on each machine or have another DHCP server!) So in a strange way I guess you can say the router is the "server" but its not used at all really for hostname broadcast except to connect the LAN machines to each other.

Try going to a command line on your machine and type
hostname
all by itself - it will return the name of YOUR computer.
Or type
ipconfig /all
it will show all the details of hostname, domain, Ip and more.

Answer 2

LANs can use DNS (a DNS server needs to be on the LAN and know about the machines on it).

Machines can also get hostnames from the hosts file (burried deep inside system32 on Windows systems and in /etc/ on *nix systems).

I believe some systems can use the name broadcast over SMB (Windows File & Print Sharing) for host name resolution.