Adobe Site not working using dedicated IP egress addresses

Products

• Cloud Secure Web Gateway - Cloud SWG

Issue/Introduction

We are testing a number of applications requiring dedicated egress IP addresses in Non-Production tenant.
All appear to work successfully with the exception of an Adobe service that seems to be causing an issue.
Only a small subset of Adobe applications are impacted - hitting Adobe applications on other dedicated IP address domains work fine.
When users access the site via browser, the default browser error page is rendered claiming that it can't reach this page with a connection reset showing.
Requests for this site are visible in the proxy log, but for the ones not working it shows tcp and ssl connections but with no https connection or any egress IP.

Environment

Dedicated IP address feature enabled.

Adobe SaaS application.

Cause

Incorrect entries in upstream DNS server hosting entries for the Adobe domain.

Resolution

Worked with Adobe to address DNS issue.

The dedicated IP address gateways could not resolve the domain correctly and could not connect to the correct server as a result.

Additional Information

The SOA/NS records for this specific destination host are broken within DNS; meaning the authorities of "sample.sites.example.com" do not know who the authorities of "app.sample.sites.example.com" are. This issue is causing recursive DNS forwarding for the lookup to break as it hits a point where it just can't get farther and never end up with an IP address for this domain.

Other lookup methods using the full FQDN or its initial sub-domain, like "dig +trace", work because the name servers for those subdomains are there and functioning. 

The actual resolution from the Adobe side was to remove an NS record from the parent domain.