Domain name services are one of the fundamental components of the internet.
Domain name services or DNS provide the mechanism where by names can be used to identify computer hosts. Inside the corporate LAN you can get away with using proprietary name services like "WINS" (Windows Internet Name Service) which is Microsoft's implementation of NetBIOS Name Service or Sun's Network Information Service (NIS or NIS+). You could use the Lightweight Directory Access Protocol (LDAP) an IETF standard directory service to implement the DNS naming convention, but once your on the internet you have to have to use DNS.
DNS maps or translate what are called "symbolic names" (eg. "www.citylinux.com" to internet protocol addresses in this case "194.159.169.244"). DNS is just as good at mapping hosts names on the Local Area Network to IP addresses too. Whether its a handful of desktop machines in a small office, or thousands in a large corporation or millions on the internet DNS can handle that mapping with ease and aplomb.
Usually we want a different view of the computers inside our network or domain from that the outside world sees so we configure the DNS server with a split horizon. We can use the internal server however to resolve external addresses out on the internet too. The DNS server is configured to forward those names it can't resolve to external internet DNS servers.
Whether you want DNS installed and configured for the first time or support for an existing DNS server I can help. Check my standard rates or call on 0709 229 5385 to get a price for your specific needs.