I mentioned before that I was able to join my machine to the active directory after updating the /etc/krb5.conf. However, there was still an error even though the join had been successful. The error was:

No DNS domain configured for mymachine. Unable to perform DNS Update.
DNS update failed!

I found an article about how to fix this problem. The fix is to modify the 127.0.0.1 entry in the /etc/hosts file. I have mine like this:

127.0.0.1 mymachine.mycompany.com mymachine