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.

The system enters ROM monitor mode if the router does not find a valid operating system image, or if a user
interrupts the boot sequence. From ROM monitor mode, a user can boot the device or perform diagnostic
tests.
Answer option A is incorrect. If the router does not have a configuration file, it will automatically enter Setup
mode when the user switches it on. Setup mode creates an initial configuration.
Answer option B is incorrect. Privileged EXEC is used for setting operating parameters.