I guess the tittle says it all: I installed apache on my ubuntu(11.10), which repository do I add to automatically update it?
Apache will automatically update to the latest available version for your distribution if you installed it from the Ubuntu repositories via any of the available methods: Software Center, Synaptic, or
Sometimes the very latest versions of software are only available for the latest Ubuntu version, which yours is not. You may want add the Ubuntu repositories
Here's how you'd add those two from the Software Center: