A security analyst noticed a colleague typing the following command:
`Telnet some-host 443’
Which of the following was the colleague performing?

A.
A hacking attempt to the some-host web server with the purpose of achieving a distributed denial of
service attack.

B.
A quick test to see if there is a service running on some-host TCP/443, which is being routed correctly
and not blocked by a firewall.

C.
Trying to establish an insecure remote management session. The colleague should be using SSH or
terminal services instead.

D.
A mistaken port being entered because telnet servers typically do not listen on port 443.

Explanation:
B: The Telnet program parameters are: telnet <hostname> <port>
<hostname> is the name or IP address of the remote server to connect to.
<port> is the port number of the service to use for the connection.TCP port 443 provides the HTTPS (used for secure web connections) service; it is the default SSL port. By
running the Telnet some-host 443 command, the security analyst is checking that routing is done
properly and not blocked by a firewall.
Incorrect Answers:
A: The telnet command parameter used by the colleague is done to check what service is running, i.e.
HTTPS, not an attempt to get a denial of service attack.
C: TCP port 443 will not allow an insecure remote session because is the default SSL port.
D: TCP port 443 is the default SSL port and SSH makes use of TCP port 22.

https://support.microsoft.com/en-us/kb/290051
Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, p. 83