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Whitelisting of content streams based on ON24 and ON24 partner URLs and IP addresses to ensure the ports and protocols are allowed.

Whitelisting Streams

Your event may incorporate streams from presenter to ON24 as well as from ON24 to the audience. Both can be whitelisted to ensure a high-quality experience. If you have presenters in your network utilizing Webcam, Screenshare, or PC Mic audio/video sources, you may benefit by having your IT Team ensure that the ports and protocols used to transport the streams are allowed. 

Audience streams are scaled using CDNs. We provide the domain URLs below to allow/whitelist content used in ON24 webcasts. We cannot provide the IP addresses for all of our CDN partners. If your company cannot whitelist streams based on URLs please contact technical support well in advance of the event to determine if another option can be provided.  We can provide some address info, and may be able to configure the CDNs used so that your events utilizes CDNs with address information available.

Both audience streaming and the presenter-focused whitelisting information is provided below.  This guide describes whitelisting requirements only for ON24 HTML5 use cases.  Older Flash-media based information is available by request to the ON24 Platform Support (

Note: This information is updated as sources in use and CDNs change.  This document should be referenced from this page each time the information is needed.  

While we strive to keep the list up to date, the CDNs modify their IP ranges without notice. We also update the list of domains in use.  Please open a technical support case if you encounter any issues. 

 Audience Use Cases

If you whitelist via domain names, below is a list of source domains:

Audience Use Case        
    Static Content   
    HLS (Mobile)   
    ON24 App Servers

If you require IP addresses, split tunneling configuration, and load-related assistance:

ON24 IP address range is 

CDNs do not generally provide IP addresses. 

If you require IP addresses to whitelist traffic for a Town Hall session (large internal meeting), please submit a case to ON24 at  We have CDN capabilities with known IP addresses to support these use cases, but we need to ensure that the event configurations are adjusted to match the whitelists you are applying.

Presenter Use Cases


For those using ON24 Broadcast Video Module, the encoder will transmit from your venue to ON24's ingress servers.  These destination addresses are:

  • -,
  • -,

The encoder devices require outbound access to these IP addresses on TCP Port 1935; the encoders are not generally proxy aware.

IP Address for ON24 Email Server

If you wish to whitelist email from ON24, email is served from:

Email Server Domain Names = = = = = =

ON24 IP Range

Proxy Server Settings

SSL Decryption should be suppressed  - Many proxies, especially the Cloud proxies such as provided by Zscaler routinely recommend decoding SSL traffic.  This is a moderately bad call in the webcasting use case for several reasons (see below).  The ON24 stream sources should be white-listed, and SSL decryption disabled.  


  • Video chunks, assuming the bit rates used in ON24 streams, will generally be about 250k bytes per chunk, with a chunk coming every 2 seconds.  This volume and frequency is greater than that assumed in configuring proxies, generally, and will cause queue times  on the SSL decode to be more highly variable than expected.  Variable queue delay gives you 1) buffering 2) exposure to lip sync issues, as audio and video chunks are separate data streams.
  • In an "Town Hall" scenario, there might be hundreds or thousands of streams being simultaneously pulled through the proxy; if decoding is specified, delivery timing anomalies are likely to be very common.
  • There is no benefit to decoding the streams; they are innocuous on their own, and the properties which deliver them are specific to ON24, so not subject to delivering other types of (potentially dangerous) traffic.
Other free/un-gated ON24 Webcast Elite and other platform content is available at
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