Firewall ensures client server security.

The body scan for security comes within the category of biometric system.

Biometric systems is a client server protection method not a problem.

Trojan Horse is a program that performs desired task but also executes some unexpected task.

Worm is a self replicating program that is self contained and does not require a host program.

Message overloading occurs when anyone sends a very large file to a inbox in every few minutes.

Wireless connections are not a threat to a server. It is just a way to connect client to server.

Firewall protects the internal network of organization from the outside world.

ICMP (Internet Control Message Protocol). A network management tool of the TCP/IP protocol suite.

The network protocol NNTP is used by the USENET news server.

Data security is not the feature of message security.

Intrusion detection cannot be done by the firewall, i.e.,  if internal employee will do the cheating then it cannot be handled by the firewall.

Public key cryptography uses two keys: public key and private key. Information is encrypted by private key and decrypted by public key.

DES (Data Encryption Standard) was introduced in 1975 by IBM.

RSA is a public key cryptosystem for both encryption and authentication.