When a TCP health check responds as “healthy” then, .

A.
the SG is able to successfully establish a TCP handshake to the upstream device.
B.
the SG is able to successfully resolve the hostname of the upstream device.
C.
the SG is able to successfully connect to the upstream device on port 80.
D.
the SG is able to successfully ping the upstream device.
Correct answer is B
The correct answer appears to be A.
“TCP [User-defined health checks] Establishes that the TCP layer connection can be made to a port on the host. The connection is then dropped.”
B would be for a DNS health check, C would be for HTTP health check, D would be for ICMP health check.
Reference:
BCCPP Course v4.3, p. 133
Correct answer is B