Mark Karpeles has created something that most people would think he's crazy for - a DNS daemon written in PHP:

If you want to tell me I'm crazy, you can post it in a comment here, it makes me happy. I had some reasons to dislike bind9 which finally made me write my own DNS daemon, and I'll explain that here. My need was to have a stable dynamic DNS server working in most environments, with an easy to configure master/slave relationship (with realtime synchronization), and a way to change records instantly from PHP...

Rather than using the (slightly unstable) dlz technology to pull the information from a MySQL database, he opted to roll his own that includes support for:

• RFC 1035 standards
• realtime data update
• slave/master relationship (with a keepalive connection)

Want to try it out for yourself? Drop him a line and ask about it!

He's also run some statistics on the performance of the daemon as compared to the standard BIND installation and come up with some instructions on how you can install and configure your own instance.

On the Solar blog Paul Jones has posted about a new database adapter they included in the latest Solar framework release - one that lets you connect to master/slave MySQL setups.

With Solar, you connect to SQL databases using the Solar_Sql factory class, which returns a Solar_Sql_Adapter class for you. Most developers only need to connect to a single MySQL server. [...] However, when you get into a situation where you need to scale up, you might need a replicated MySQL database setup. In such cases, there is one "master" server that handles reads and writes, and there are one or more "slave" servers that are read-only.

The Solar_Sql_Adapter_MysqlReplicated adapter does all of the switching for you, making it as simple as dropping it in and changing your configuration to point to the master and slave servers (examples included).