Computer Network

 16. Define substitution & transposition encryption?

.           Substitution: A character level encryption in which each character is replaced by another character in the set.

Transposition: A Character level encryption in which the characters retain their plaintext but the position of the character changes.

17. Define CGI?

.           CGI is a standard for communication between HTTP servers and executable programs. It is used in crating dynamic documents.

18. What are the requests messages support SNMP and explain it?

·         GET

·         SET

The former is used to retrieve a piece of state from some node and the latter is used to store a new piece of state in some node.

19. Define PGP?

            Pretty Good Privacy is used to provide security for electronic mail. It provides authentication, confidentiality, data integrity, and non repudiation.

20. Define SSH?

            Secure Shell is used to provide a remote login, and used to remotely execute commands and transfer files and also provide strong client/server authentication / message integrity.