if you have your own server/static ip , do you run your own name server?
It depends....
Just because your IP address is assigned to you statically instead of dynamically doesn't mean that you suddenly have to start providing for your own DNS services! Typically, your ISP will give you these four items: an address, a subnet mask, a gateway, and a set of DNS servers.
Now lets say that this computer is going to be a web or file server. At this point, you still do not need to run your own DNS server. If this is for private (home/SOHO) use, you can just give people your IP address, or a hostname given to you by your ISP. For example, "host27.user16.sea.wa.myisp.net".
If you purchased your own domain name, then things change. You can pay an external company to setup your domain on their domain servers and point it to your static IP addresses, but they are going to charge a few dollars a month for it. On the other hand, you can do it yourself. Just keep these things in mind:
[*]On UNIX servers, the DNS service (named) is one of the most targeted services for hacking. A successful hack will give hackers administrative access. You will need to keep on top of updates on a monthly, if not weekly basis, to keep your machine safe.
[*]On UNIX servers, it is recommended that you run the DNS service on a stand-alone server. That said, free flavors of UNIX, such as BSD and Linux, run quite well with modest hardware. My DNS server, which runs on FreeBSD and handles six domains, runs on a Pentium/133 with 64MB of memory.
[*]On Windows servers, the DNS service is also a heavily targeted service for hacking, although not as much as with Unix. That said, a Windows server will be more vulnerable to worms and viruses that hit the Internet. You will need to stay on top of service packs, hot patches, virus definitions, and such.
[*]If you're using Windows and you plan on isolating your DNS services onto its own machine, keep in mind the cost: Microsoft no longer updates the DNS server on Windows NT, so you will be paying hefty for Windows 2000 or XP Server. Furthermore, these OSes need beefy hardware: a Pentium3/850 with 512MB of memory is a starting point.
[*] There are other costs, such as power, server hardware, mantime, ect. If you have a single DNS domain and don't plan on making many changes, an external DNS hosting service may not be a bad idea. Its also nice when things ah heck up, since you have a live person to yell at instead of a hunk of metal and plastic. Let THEM deal with fixing it.