It can be anything! An apex, subdomain, or even a URL.

Results forprimary.us.email.fireeyecloud.com

Resolver

Location

A

Name	TTL	Value
primary.us.email.fireeyecloud.com	300	3.93.93.43AWS EC2 (us-east-1) / Amazon Technologies Inc.
primary.us.email.fireeyecloud.com	300	3.93.93.44AWS EC2 (us-east-1) / Amazon Technologies Inc.
primary.us.email.fireeyecloud.com	300	3.93.93.45AWS EC2 (us-east-1) / Amazon Technologies Inc.
primary.us.email.fireeyecloud.com	300	34.223.36.124AWS EC2 (us-west-2) / Amazon.com, Inc.
primary.us.email.fireeyecloud.com	300	34.223.36.125AWS EC2 (us-west-2) / Amazon.com, Inc.
primary.us.email.fireeyecloud.com	300	34.223.36.126AWS EC2 (us-west-2) / Amazon.com, Inc.