'Looking-Glass' Tool Released by Blizzard
Use the tool to diagnose issues connecting to Blizzard servers and games

Looking-Glass can perform a ping, traceroute, or the combined MTR. This information can be used to diagnose where a problem may be in the many hops from a home computer to Blizzard's servers. This can always be done with programs on the PC, as detailed in a Battle.net support article. The benefit of Looking-Glass is that you don't have to run any programs yourself, it does all the work for you. If you have connection problems to Blizzard's servers down the road, keep Looking-Glass in mind to help narrow down the issue.