If you're looking for a backup tool, you should use backup software - Chef is a configuration management tool, which approaches it from a different perspective.
Using config management, the configs are stored in the tool and pushed to the servers. Throw a server in the trash and put a new one in with the same name, and it should have its configs pushed to it. But that won't take care of data files.
Using backup software, the servers' data is copied to tape or other storage. Server dies, you put a new one in and perform a restore - ideally of everything. Plus, backup software is optimized for (wait for it... ) backups. Tape/media management, streaming to multiple devices/libraries, etc - you sure you want to try to reinvent that wheel using a tool made for something else?
Now, your title mentions a lot of things. AD is part of the System State of every DC in a given domain. Back up the system state, you have AD inside it. Because of the multi-master nature of AD, you have to be careful about restoring DCs with normal backup software, with regards to tombstones and authoritative restores.
DHCP - the config for the server is stored in the registry (again, typically backed up in System State) and the config for the scopes is backed up regularly on the filesystem. So, you'd want to get both of those.
DNS, if it's AD-integrated, is part of System State as well. If it's standard zones, then it should just be text files in the OS.
IIS 6 and prior used the metabase to store the configs; not sure what 7.x is using off the top of my head. But that's just the configs - you typically want the files under the sites and VirDirs, too.
Exchange - I'm not sure that the "config" for exchange is stored separately from doing a backup of Exchange as a whole, which you should absolutely doing. Your users won't be too happy if your mailserver craps out, and you can't bring their mailboxes back, but saved yourself an hour of configuring your replacement server because you had the config saved.