Question

In computers, a firewall is a/an
(1) established network performance reference point.
(2) software or hardware used to isolate a private network from a public network.
(3) virus that infects macros.
(4) predefined encryption key used to encrypt and decrypt data transmissions.

Answer 1

here is ur answer

2) software or hardware used to isolate a private network from a public network

Answer 2

A firewall is a/an (2) software or hardware used to isolate a private network from a public network.  

Firewall

• A firewall is a network security mechanism that analyses incoming and outgoing network traffic and determines whether certain traffic should be allowed or blocked based on a set of security rules. Hardware, software, or both can be used to create a firewall.
• A firewall's goal is to create a wall between the internal network and incoming traffic from other sources (such as the internet) in order to prevent harmful traffic such as viruses and hackers from entering.