Again, it's best to talk to your accountant about the best way to establish your chart of accounts and items to meet your business needs. I'm only offering "things to think about" as opposed to accounting advice. Your requirements will be unique to your specific business, so only you can decide what's "best" for your business.
The same comments I made before apply whether you're only recording expenses or whether you're recording both revenues and expenses for an item. Since you're creating "service" items for domains, nothing is hitting inventory so all tracking/analysis takes place through GL reports (trial balance, balance sheet, income/expense, etc.) If you don't need to separately track/analyze expenses for internal domains, then creating one item called "internal domains" will do. But, if you need to analyze/track expenses for internal-only domains separately, then your choices are:
create individual items for each internal domain, or
create separate GL expense accounts for each internal domain
The latter way (separate GL expense accounts for each internal domain) gets messy quickly, but if you only have one or two internal domains and not a lot of GL expense accounts it's doable.
Anyway, the "bottom line" is what you think your future reporting/tracking/analyzing needs are going to be. Think very long and hard about this NOW, before you start entering transactions into FA. While you can change things around later, it gets quite time-consuming and messy doing so, and you'll lose the consistency and continuity in your records. So, it's better to decide one way or another now and stick to it rather than rushing into a decision and finding out later it should have been done another way.
Hope all this is helpful. Again, maybe have a chat with your accountant.
Regards,
Chris