Overview

When browsing the internet sometimes the pictures, videos and interactive content is not hosted on the same domain as the website itself.

In the below example, the website in the URL bar is 'amazon.co.uk' however the images are actually hosted on 'images-na.ssl-images-amazon.com.. This is a crucial part of how websites with multiple styles of content operate and these background resources are called CDNs or Content Delivery Networks.

When websites and network traffic go through Securly Filter there may be traffic from these Content Delivery Networks or background resources that are blocked for various reasons.

When blocked background has been identified it needs to be allowed for the content to be accessible. Please see this KB to see how to add a domain to an allow list.

These resources by be explicitly blocked because of the category of website they are or they may be blocked due to customer configuration on your filtering instance.

To find these background domains open your browsers 'Developer Tools'. Typically this is under 'More Tools' on Edge and Chrome or you can use 'CTRL+Shirt+i' to open the Developer Tools.

Developer Tools: Console

Within the Developer tools if any websites are blocked they will show as an error in the console tab of the Developer Tools:

The wording of any error messages can vary based on how or why the content is blocked however typically anything in red indicates a block or content not loading.

Note: If a HTTP code is referenced in any error message please review the HTTP code as this will provide further information about why the content may not be loading/loaded.

Developer Tools: Network

Within the Developer Tools network activity can be monitored from the Network tab this will include all successful and most unsuccessful requests.

The network tab shows all information about the background activity on any website that is accessed and it will show all domains and subdomains that are part of the website. In most cases errors or problems will show in red however this is not always the case.

In most cases if a copy of the network activity is required this will be specifically requested by the Securly Support team.

To find out how to export the network logs as a HAR file please see this KB.

How to view background content on a website