Configuring a Domain Controller for an Internal Domain in Windows Server 2012

You should own the domain you're using, so in your example, you need to own domain.com. You do not, however, need to create any DNS entries for it, either on your internal LAN or externally.

If you're installing AD from scratch then you can just go ahead and install the AD Domain Services role on your server. You just supply the domain name developer.domain.com as the AD domain name.

You'll be prompted to install DNS as part of the AD installation process, say yes to this offer and it should install DNS and create the appropriate entries for you. DO NOT try and use the ISP's DNS for your domain controller or your clients. You can have your local DNS forward requests to the ISP DNS but the sever and its clients need to use the AD server's own DNS server to find each other for your local network to work properly.

While its possible to do the DNS configuration by hand, if you've never installed AD before then I'd strongly suggest letting the AD install process do this for you then looking at what its done afterwards.

This is all you need to do to create a domain that you can join computers to in a network. There's a lot of "best practice" stuff you should really be doing as well (you really should have more than one DC for a start) but this is the basic 'get you started' level.

You might find this question useful for AD background too.