Hi, you're welcome. It mainly depends on what kind of broadcast you are thinking of (which protocoll, which OSI layer?). But whatever it is, it will usually work in your local LAN or network segment only! Your ISP (or router) makes sure broadcasts on a low layer are not routed to the internet, because wild broadcasts from many many hosts could easily collapse the internet. High broadcast traffic is also a problem inside gnutella (for known countermeasures on this layer/protocoll see TTL and superpeers/ultrapeers, pong caching etc).

For example a known broadcast inside a LAN is used with Samba service (the famous file service), it broadcasts to find master servers and other file servers. Those broadcasts are usually send only to the same netwok segment, corrosponding to your TCP/IP network mask (see details in /etc/smb.conf).

Actually host caches are the only slightly centralized structure inside Gnutella. There are some alternative ideas, e.g. an IRC channel where servants exchange IPs. Any more ideas known?

PS: Sephir, the internet uses IPs. DNS translates internet hostnames to IPs, and reverse. It's a common service you need if working with hostnames (resolving to IPs). When being pure IP based there is no need to query a DNS server, the Gnutella protocoll itself is pure IP based (IPv4 yet).