Looking-Glass is a network diagnostic tool you can use to help determine where connection problems might be occurring between our servers and your computer. We may ask you to use Looking-Glass to help troubleshoot latency or other network issues.

Go to Looking-Glass

To use Looking-Glass, select your region, the service you're trying to connect to, and the tests you want to run. Look below for an explanation about what each test does.

Reading Looking-Glass Diagnostics

MTR

This test gives you an overview of what's happening with the connection from our servers to your location. Here's an example MTR to show you what's going on.

HOST:BlizzardLoss%SntLastAvgBestWrstStDev
1.Blizzard0.0%100.50.60.41.30.3
2.???100.0100.00.00.00.00.0
3.third-hop.some-ip0.0%100.50.30.30.40.0
4.fourth-hop.some-ip0.0%100.30.30.30.40.0
5.fifth-hop.some-id0.0%102.21.90.92.61.1
6.sixth-hop.some-ip0.0%103.33.21.24.91.2
7.seventh-hop.some-ip0.0%104.73.21.55.21.3
8.eighth-hop.some-ip0.0%102.32.32.22.40.0
9.ninth-hop.some-ip0.0%106.09.46.029.27.2
10.tenth-hop.some-ip0.0%104.04.13.95.80.6
11.eleventh-hop.some-ip0.0%106.06.05.96.00.0
12.twelfth-hop.some-ip0.0%106.07.25.914.63.3
13.thirteenth-hop.some-ip0.0%105.85.94.17.60.9
14.fourteenth-hop.some-ip0.0%107.97.97.98.00.0
15.fifteenth-hop.some-ip0.0%106.87.06.67.20.2
16.sixteenth-hop.some-ip0.0%107.07.07.07.10.0
17.final-hop.some-ip0.0%1020.118.913.124.03.2

The above MTR looks pretty good. There are no large spikes in packet loss or response time, and it shows a reasonably healthy connection. Here's an example MTR that has a few problems:

HOST:BlizzardLoss%SntLastAvgBestWrstStDev
1.first-hop.some-ip0.0%100.30.60.31.20.3
2.second-hop.some-ip0.0%100.41.00.46.11.8
3.third-hop.some-ip60.0%100.82.70.819.05.7
4.fourth-hop.some-ip60.0%10388.0360.4342.1396.70.2
5.fifth-hop.some-ip50.0%10390.6360.4342.1396.70.2
6.sixth-hop.some-ip40.0%10391.6360.4342.1396.70.4
7.seventh-hop.some-ip40.0%10391.8360.4342.1396.72.1
8.final-hop.some-ip40.0%10392.0360.4342.1396.71.2

You can see large spikes in response times and packet loss. There are problems with this connection, and your gameplay would suffer.

Traceroute

Trace routes can help identify where connection problems occur by testing the connection from our servers to your computer. A traceroute report shows the step-by-step path a packet of data takes to reach its destination.

If you notice any of the following problems in your traceroute report, it may indicate an issue with your connection:

  • Timeouts
  • * (asterisk) symbols
  • Number values jump from low to high
  • Numbers are consistently high

Ping

Ping is useful as a quick way to determine if the host you're trying to reach is operating. It sends packets, then waits for a response. Unlike traceroute or MTR, though, a ping test does not record the path the packet took. If our servers can't reach your computer, a ping test will let you know.

If you notice any of the following problems in your ping report, it may indicate an issue with the connection:

  • Packet loss
  • High response time

Note: Sometimes a ping will fail due to network security and not due to actual connection issues. We recommend you run an MTR to get more information about why your ping test may be failing.