DNS Failed and other problems?

Okay, I've been playing on live for about 2 months with no problems until yesterday I couldn't get on live. I tested it and it said the DNS failed and I can get on the internet and everything. Then I tested it again and all the things confirmed but I went to play Halo and it booted me out. Today the DNS failed again and then everything confirmed. Then I tried again but it said the MTU failed then the next time it said it was fine except the ICMP failed. I give up help me