A developer wants to design a custom subscription center in CloudPages. The developer prefers to code in AMPscript, but is also skilled in Server-Side JavaScript. While the developer is confident their code is of high quality, they would still like to handle unexprected errors gracefully to ensure the best user experience. Which feature should handle this scenario?

A developer wants to delete a batch of subscribers from Marketing Cloud. The developer performs a Contact Delete on a batch of records in a data extension in Contact Builder. Which scenario would cause subscriber records to remain in the data extension?

A developer uses an API to send data to a Marketing Cloud data extension once every five minutes using the REST API. They notice data does not always write to the data extension, leading to data loss.
Which three best practices are recommended to avoid this issue? Choose 3 answers

A developer initiated a batch delete of Contacts in Contact Builder due to an import error during implementation. There are over two million records that need to be deleted.
Which two factors should be considered when batch deleting large volumes of contacts?Choose 2 answers

A developer identified a use case where atriggered send of an email is needed. The developer already successfully set up authentication with a Client ID and Client Secret has used them in several REST calls.
When the REST call is made, a "401 Unauthorized" error is returned. What is the first thing the developer should check?