In today’s digital communication era sharing of information is increasing significantly. The information being transmitted is vulnerable to various passive and active attacks. Therefore, the information security is one of the most challenging aspects of communication. Cryptography plays an integral role in secure communication and it provides an excellent solution to offer the necessary protection against the data intruders. One of the cryptographic technique is a symmetric cryptography; In this technique the sender and receiver use the same key to do encryption and decryption of the data. This secret key must be shared between the sender and the receiver. Therefore this paper presents a study on distribution of key among the sender and receiver in symmetric cryptography and also it gives the study on authentication of the clients in distributed network. Many protocols are used to make key distribution among the clients and authentication of the clients in distributed network. The main two are Needham-Schroeder key distribution protocol and Kerberos protocol