RG-59 type of coaxial cable is used for cable TV and cable modems.
Answer option D is incorrect. RG-8 coaxial cable is primarily used as a backbone in an Ethernet
LAN environment and often connects one wiring closet to another. It is also known as 10Base5 or
ThickNet.
Answer option A is incorrect. RG-62 coaxial cable is used for ARCNET and automotive radio
antennas.
Answer option C is incorrect. RG-58 coaxial cable is used for Ethernet networks. It uses baseband
signaling and 50-Ohm terminator. It is also known as 10Base2 or ThinNet.

In a vanilla port scan, the scanner attempts to connect to all 65,535 ports.
Answer option B is incorrect. The scanner attempts to connect to only selected ports.
Answer option A is incorrect. The scanner scans for open User Datagram Protocol ports.
Answer option C is incorrect. The scanner goes through a File Transfer Protocol server to disguise the cracker's location.

Following are the common security problems involved in communications and email:
Eavesdropping: It is the act of secretly listening to private information through telephone lines, e-mail, instant messaging, and any other method of communication considered private.
Identity theft: It is the act of obtaining someone's username and password to access his/her email servers for reading email and sending false email messages. These credentials can be obtained by eavesdropping on SMTP, POP, IMAP, or Webmail connections.
Message modification: The person who has system administrator permission on any of the SMTP servers can visit anyone's message and can delete or change the message before it continues on to its destination. The recipient has no way of telling that the email message has been altered.
False message: It the act of constructing messages that appear to be sent by someone else.
Message replay: In a message replay, messages are modified, saved, and re-sent later.
Message repudiation: In message repudiation, normal email messages can be forged. There is no way for the receiver to prove that someone had sent him/her a particular message. This means that even if someone has sent a message, he/she can successfully deny it.
Answer option D is incorrect. A message digest is a number that is created algorithmically from a file and represents that file uniquely.