An administrator needs to do the following: install a load balancer in front of an existing application test application performance avoid reconfiguration of the application server avoid interruption

Modifying the local hosts file on the test client overrides DNS resolution only for that machine, allowing the tester to direct traffic to the new load balancer IP without changing the DNS A-record, reconfiguring the application server, or affecting any other users still resolving the original address.

Modifying the DNS A-record would redirect all users to the new load balancer immediately, causing potential disruption and violating the requirement to avoid interrupting existing users.

IP Anycast routes traffic to the nearest node based on routing topology and requires network-level reconfiguration, which does not satisfy the no-reconfiguration and no-disruption requirements.

Port Address Translation changes how ports are mapped on a network device and does not selectively route a single test client's traffic to a new load balancer without broader network changes.