Introduction
This document describes how to troubleshoot a domain or resource being blocked using Chrome Net-Internals.
Overview
Occasionally domains are being blocked by Umbrella, but you are unsure of which domain(s) were blocked or why. It is possible a blocked domain is causing problems with a secondary domain, which can happen when websites use multiple embed
In order to find out which domains were blocked because the block can be causing other issues, Google Chrome has a built-in tool that you can see a list of domains being queried as well as the IP they are resolving to. It is very handy to get that information, especially if you would like to add it to a Allow or Block list in your Umbrella.
These steps can be taken to look for this information when using Google Chome:
1) Open Google Chrome
2) In the address bar type chrome://net-internals and hit enter
3) You see this page:
4) Click the export drop-down menu and select the DNS option
5) You see a table with lots of entries as well a "Clear Host Cache" option, that option resets its cache (useful to test and make sure you are getting new data as well as a more clean state where it is easier to find the record you are looking for)
6) In this case we are using the domain example.com, you can now see the IP it is resolving to.
In the example above, you can see that example.com is resolving to 204.194.239.143 which is an IP that belongs to Umbrella, so it means it is being redirected/blocked.
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