Is it possible to have a user base reference the Servicenow URL and another user base reference a custom URL ?

All

It is **not** recommended for end users to use both the new custom URL and the original Servicenow instance URL because only one instance URL can be set at a time for URL link generation.

Custom URL configuration overview:

• 1. Purchase a custom URL from a domain provider.
          A certificate from LetsEncrypt is automatically used for custom URL configuration.
• 2. In ServiceNow, activate custom URL plugin
• 3. Add a Custom URL record by filling in Domain name(your custom URL) and choose a service portal url to redirect users to when they access instance using custom url.
• 4. Submit. ServiceNow takes upto 6 hours to complete custom URL creation.
• 5. The instance administrators receive an email when custom URL is "Active".
• 6. Once the URL is "Active", set it as instance URL by clicking the "Set instance URL" button.

This will result in the custom url being used for all outbound urls.
glide.servlet.uri updated for ${URI} and ${URI_REF}.
glide.email.override.url

Please note that only one instance URL can be set at a time for URL link generation.