You mentioned DNS in the subject and then ask about a personal domain name - I assume you are referrring to the latter as a personal DNS doesn't really make much sense.
Your Domain name is like real estate - If you start a website or blog on a free website is like building your home on land you borrowed - would you do that ? I wouldn't .
The cost of a domain name + additional services, systems and administration are well within reach for anyone - even the smallest budget - it's just that inexperienced people like the sound of that word FREE and only when it's too late they realize what a mistake they made. I read situations like this all the time in forums.
So go for it buy your domain name and use it - build your home on YOUR land ;-)