What are the advantage and disadvantage of security in computer network?

First the advantages. A secure network has much less likelihood of unauthorized access which could result in corrupted data, stolen data, or malicious damage to a database. Some form of encryption is usually used to make data unreadable even if it is stolen. The chief disadvantage is slowdown of the system. Encrypted data must be un-encrypted, users have to be verified, some IP addresses have to be blocked, etc.