Is it OK to have one domain for all your landing pages?
It seems like a pain (and a waste of money) to buy and setup a domain for every offer. I'm hoping that it's perfectly fine to use one generic domain for all my landing pages. I'm starting with mobile offers, if that makes any difference.
You should always be vary about centralizing stuff like this. You'll be easier to pick apart by your competitors.
For testing purposes I have a few "centralized" domains where I run multiple offers/landing pages from. I'll often use something like those com-net.com domains (not mine, sorry if I'm outing anyone lol) and then just set up subdomains.
But this is just for the initial run and/or test. If it takes off there's really no excuse for not setting up its own domain. And seriously, is $10 really "expensive" in the grand scheme of things? At least for me, I like to run stuff that'll make me more than $10 
Hope that helps
Buy generic domains for different verticals, hell even different campaigns or traffic sources.
It's just an alias, a vanity thing, but the domains can have a minor impact on user perception.
For affiliates, it is more about spreading your footprint and throwing away aliases like burner phones.
I buy .pw domains because they are ~$4.
If you are starting out I wouldn't worry about different domain set ups. Just buy something generic like web-1.us and then add sub domains like download.web-1.us. Once you start running volume then you can switch domains up.
Thanks, Everyone, for your replies.
I'm not concerned being picked apart by my competitors just yet. Sounds like a good problem to have - being successful enough that people would bother. I like the idea of waiting until a campaign is successful at volume before buying its own domain.
I have split tested in the past and the domain makes a very small change in ROI.
So if you are starting out just use 1 domain and get more if camps do well.