Blocked sites in Turkey and DNS numbers (Istanbul)

Hello!

I've noticed that several harmless internet sites in Turkey seem to be blocked for whatever reason. I was able to get around this and able to access them by changing my DNS numbers but after a few days, those codes seem to deactivate and new ones need to be used yet I'm unsure as to where to find ones that will allow me access. Any suggestion would be greatly appreciated.
Thanks so much!