Question: When looking through the questions I saw one which was edited by community, I read somewhere that community bot does this to bring attention to old unanswered questions I always thought it was bad to answer questions that aren't that recent.

Is there a cutoff point where you shouldn't answer a question? Or is it still good to answer a year old question?

Answer: 
By all means.. answer **anything and everything** if you can. Don't even look at dates :)

Questions get bumped for a number of reasons. I think the only "annoying" reason is when some random person posts a "thank you" as an answer. Other than that... I wouldn't worry about bumping anything.

While old questions have a far greater chance that the user will *never* return to mark something correct.... Google still finds the question and answers could still benefit any number of people searching for a solution.
If you have an answer to a question that adds quality to the question by all means provide an answer. There is no time length on answering questions. We do frown upon reviving old questions with a crappy answer and usually people adding answers to an old question are either new, one line answers, or spam aka link only answers.

Community will bump a question that has answers if the answer have no up votes or if the question only has one answer that is not accepted.