We know that word :Ask is a common word and i think can't be trademark. But i see that ask dot com have R letter in circle near logo. Did this mean that logo is protected like a trademark or for word ASK globally? Sincerely
Common words can certainly be trademarks, just not for their common usage. Example is that Apple is a trademark for a computer/phone/music company but not for fruit. Ask.com is not the same as ask. The full name could be trademarked, as well as the image logo. Read more on basic trademark law here: http://www.uspto.gov/trademarks-getting-started/trademark-basics