Adding More Domains

To add a new domain to your server you just add the needed forward and reverse zones in your named.conf file(s). There is no limit in BIND on how many zones it can serve, but in practice it is limited by how many requests your server can handle, and how fast it can be restarted and/or reloaded. There are BIND nameservers, in production use, that uses more than 30 minutes to start, just because of the number and size of the zones they serve. In BIND 9 we have been promised ways to solve this problem by using back-end databases, so that BIND can load records on demand, rather than a whole zone at a time.

It is reasonable to expect that any modern computer can handle the load of several hundreds of zones depending on the size and popularity of course. One thing you should note is that BIND loads all the zones in entirety into memory. You will need enough RAM to store all of BIND, without swapping for preference. Additionally the cache will use up your RAM. In principle BIND will continue to use memory as long as it needs it and can. In practice few people have a problem with this. If this scares you, please have a look at the section on BIND resource limits in Chapter 8.