FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Article Id 301363
Description This article describes how to fix some cases of slow webpage loading by whitelisting the ad-serve domain integrated with the site.
Scope FortiGate version 6.4 and above.
FortiGate version 7.0 and above.

Sometimes, web pages load slowly when browsing specific websites ( will be used as an example in this article).


webpage slow.PNG


In this example:

  • The website falls under the News and Media category, under the group 'General Interest - Personal', through web filter lookup.
  • The web filter profile enabled in firewall policy and the category has been allowed, so this behavior is unexpected.


To resolve the issue, take the following preliminary steps first:

  • Determine whether the website is using any form of advertising.
  • In this case, it was noted that the website queried multiple advertisement domains when the page loaded. Because the advertising category has been blocked in the web filter profile, this slows page loading.
  • Check the web filter logs to verify whether any ad serving URL is being blocked.

There are two solutions:

  • Enabling the advertising category can fix the issue, but this is not a recommended configuration for many customer environments.
  • An alternate solution is to whitelist the ad-serving domain integrated with the website. This article explores that option further.


To determine the list of domains an advert depends on, install adam:One Assist in the browser as extension. Once the page loads, select the extension button to view the domain list and choose the one ad-serving domain to whitelist.


adamone assist.PNG


To view the exact domain of the advertisement, use the developer tools built into Chrome: right-click on an advertisement and choose 'Inspect'. This will open a split screen view that shows the web page's information, including the necessary information for this solution: the domain name the advertisement is coming from. After identifying this domain, add it to the web content filter whitelist.


ad-serve domain.PNG


Related article:

Technical Tip: Using a static URL filter feature to allow/block web sites.