We've been having an issue the last few days where users from the eastern U.S. and various European countries cannot connect to my company's sites, but only sporadically. I've been using this tool to test:
Please note that you may need to hit refresh a few times to see the red Xs.
The first domain listed above recently had its DNS changed to Amazon from GoDaddy in the hope that having distributed DNS servers (including one in the U.K.) would help. It does seem to have helped a little so far (not seeing red Xs in London at the same frequency), but there are still some locations (Berlin, Moscow, etc.) that are still showing as such. The second and third domain above are still using GoDaddy DNS.
My best guess is that there is a problem server (routing or DNS) on the eastern part of the U.S., since (1) that is the gateway to the U.S. from Europe and (2) I've seen lots of red Xs in Boston and a few in New York, but no other U.S. cities. Unfortunately, any traceroutes I've received from users so far show the complete route to our server with no signs of failure (problem is sporadic, as mentioned above).
Any recommendations on how to go about troubleshooting something of this magnitude?
I tested each of the URLs above 10x and got the following:
http://www.whatsmydns.net/#A/www.vitalmtb.com = 20 failures (Berlin, Germany x 4; Merzig Saarland, Germany x 6; London, United Kingdom x 5; Moscow, Russia x 2; Portland OR, U.S. x 3)
http://www.whatsmydns.net/#A/www.vitalbmx.com = 21 failures (Rome, Italy x 7; Moscow, Russia x 2; Berlin, Germany x 5; New York NY, U.S. x 3; Boston MA, U.S. x 4)
http://www.whatsmydns.net/#A/www.vitalmx.com = 18 failures (Rome, Italy x 4, Berlin, Germany x 6; Ankara, Turkey x 1; London, United Kingdom x 1; Rome, Italy x 2; Moscow, Russia x 4)
You may disregard my above statement about how changing DNS from GoDaddy to Amazon helped, because based on these results it did not. Again, the first one is using Amazon's Route53 DNS and the latter two are currently using GoDaddy DNS.