Final answer:
Whitelisting the entire set of IP ranges is a best practice because it prevents service disruptions during instance switches, reduces the need for verification codes, allows easy access for users across various locations, and ensures Salesforce login authentication processes are not hindered by IP restrictions.
Step-by-step explanation:
Whitelisting the entire set of IP ranges for your region is considered a best practice for several reasons. First, it avoids unintended service disruption which can occur when services switch between primary and secondary instances due to various reasons such as maintenance or outages. By whitelisting all the IPs in a region, you ensure continuous service availability without interruption. Second, it minimizes the use of verification codes for logins, resulting in a smoother and more time-efficient experience for both users and administrators.
This is particularly important in environments where frequent logins are required, and two-factor authentication can greatly slow down the process. Third, whitelisting allows users to access Marketing Cloud from any work location without the need for additional layers of authentication, providing ease of access while also maintaining security. Lastly, whitelisting ensures that Salesforce login pools can properly process login authentication requests for end users when they try to access Salesforce, preventing potential access issues due to IP restrictions.