If a third-party or custom creative isn't rendering correctly on your website or when you preview it in DFP, you can create a test page to help identify the problem. The test page can show you whether the creative renders properly when it's independent of the other code on your website.
The following instructions outline the process of creating a test page. Since the actual steps may vary depending on your particular environment, please reach out to your web developer or I.T. team if you have questions about how to complete this process at your organization.
To create a test page:
Open a plain-text editor (such as Notepad or TextWrangler) and place the following code in a blank file:
Copy and paste your creative code into your text editor in between the
Save the code as an HTML file.
Upload the HTML file to the web server that hosts your web content. This step is largely dependent on your web host configuration, so your web developer or IT team should be able to help you if you have questions about how to complete it. Alternatively, if you cannot upload the page to a web server, you can save it locally.
Visit the URL (or file location) for your test page and ensure that the ad tag functions properly using multiple web browsers (for example, Chrome, Firefox, Safari, and Internet Explorer) and operating systems.