Confidentiality, Integrity, and Availability Explained

Confidentiality, Integrity, and Availability are security terms. Security professionals use these terms to refer to many aspects of networking. This tutorial explains the meaning of these terms in detail.


Confidentiality protects sensitive information. It blocks unauthorized access. It refers to a situation where only authorized users are allowed to access the information. Administrators use several methods to maintain confidentiality. Some common of them are the following.

  • They configure permissions on files and folders to block unauthorized users and applications from accessing them.
  • They encrypt the data in storage devices. Only users with the decryption key can gain access to the data. It is known as encrypt-in-storage.
  • They encrypt the data as it travels across the network or the Internet. It is known as encrypt-in-transit.


Integrity ensures that the data that is accessed is in its original state. For example, you create and store a file on the file server. One month later, you access that file again. How will you know the file has not been tampered with or altered? You can use technologies that offer integrity services to identify whether the file has been modified or is in its original state.

Hashing is one of the most widely used techniques to prove integrity. It runs a hashing algorithm on the data and generates a hash value. The generated hash value is used to verify the integrity of the data. You must save it in a safe place for reference. Whenever you want to check the integrity of the data, run the hashing algorithm again, and compare the result with the saved hashed value. If both values match, data has not been altered. If both values do not match, data has been altered.

Message Digest 5 (MD5), Secure Hashing Algorithm 1 (SHA-1), and 256 (SHA-256) are examples of hashing algorithms.


Availability ensures the data remains available whenever the user needs it. For example, if a user saves a file on the file server, the user expects the file to be available on the server whenever he wants. Administrators use many technologies to increase the availability.

Some commonly used techniques are the following.


Administrators regularly take backups of all critical data and save the backup copy on a remote site. Backup copies allow them to restore the data in case of accidents or server crashes. Saving backup in a remote location eliminates the chance of data loss in the event of a natural disaster.


RAID deploys multiple hard drives in an array. If a drive fails, data remains available on other drives of the array. Users do not face any downtime.


Cluster functions similar to a RAID but deploys multiple servers for the same applications. If one server fails, applications remain available on the other servers of the cluster.


FHRP provides redundancy for routers. If a router fails, another router takes over.


Confidentiality means the data is accessed only by authorized users. Integrity means the data accessed in the original state. Availability means data remains available all the time.

ComputerNetworkingNotes CCNA Study Guide Confidentiality, Integrity, and Availability Explained