Configure dynamic advertisement

​​ Before you start (Magic Transit customers only)

If you are advertising a new prefix or enabling the advertisement of an existing IP prefix (changing it from Withdrawn to Advertised), make sure you disable Advanced TCP Protection first.

After enabling the prefix advertisement or advertising a new prefix, do the following:

1. Ensure that the traffic is being successfully routed via the Cloudflare network. Check the Network Analytics dashboard or use traceroute Open external link to analyze the path IP packets are taking.
2. Re-enable Advanced TCP Protection.

​​ Configure dynamic advertisement via the dashboard

To configure IP prefix assignment from your Cloudflare account home, use the Status drop-down list in the IP Prefixes dialog, as outlined below.

1. Log in to your Cloudflare dashboard.
2. Navigate to Account Home > IP Addresses > IP Prefixes.
3. To edit a prefix, select Edit at the end of the entry.
4. From Edit IP Prefixes, under Status, select Advertised or Withdrawn.
5. Select Save to commit your changes.

After saving your changes, it takes between 2 to 7 minutes to enable advertisement and approximately 15 minutes to disable (withdraw) advertisement.

​​ Configure dynamic advertisement via the API

To configure prefix advertisement with the Cloudflare API, use the IP Address Management and Dynamic Advertisement API.

Most dynamic advertisement operations require that you supply the Cloudflare ID for any prefix you want to access with the Cloudflare API. The following section outlines how to obtain Prefix IDs.

​​ Obtain Prefix IDs

You can obtain Prefix IDs from the IP Prefixes page in your Cloudflare Account Home.

1. Select the expander for the entry whose Prefix ID you want to obtain.
2. To obtain the Prefix ID, refer to the API Tag value. To add the value to your clipboard, select Copy.

To obtain Prefix IDs using the API, refer to the List Prefixes operation in the Cloudflare API.