To ensure seamless connectivity during (and after) migrating an application server, the best DNS approach in CompTIA A+ Core 1 (220-1201) terms is to use a CNAME (Canonical Name) record, which creates an alias from one hostname to another. Instead of users connecting directly to a server's changing hostname, they connect to a consistent service name (for example, app.company.com). That name can be configured as a CNAME pointing to the current host (such as server1.company.com). When the application is moved to a new server, the technician updates what the alias ultimately resolves to (or updates the target host's A/AAAA record), and clients continue using the same familiar application URL/name-minimizing disruption and avoiding the need to reconfigure endpoints across devices.
The other record types are not designed for this purpose. TXT records store text-based information (often verification or policy data). SPF and DKIM are email authentication-related mechanisms (typically implemented via TXT records) used to validate authorized mail senders and message integrity-not application server migration. Because the goal is maintaining a stable name for a service while the underlying host changes, CNAME is the correct record type.