What is the function of NAT?

A.
It performs Layer 3 routing.

B.
It evaluates and redirects matching traffic into secure tunnels.

C.
It provides translation between public and private IP addresses.

D.
It performs Layer 2 switching.

Explanation:
Historically, the NAT concept was born because of the shortage of public IPv4 addresses. Many organizations
moved to deploy so-called private addresses using the IPv4 private addressing space, as identified in RFC 1918.
These addresses include the following ranges:
• 10.0.0.0–10.255.255.255 (10.0.0.0/8 prefix);
• 172.16.0.0–172.31.255.255 (172.16.0.0/12 prefix); and
• 192.168.0.0–192.168.255.255 (192.168.0.0/16 prefix).
Because private addresses are not routable within the public domain, edge network devices can deploy the
NAT feature to replace private, nonroutable addresses with public addresses prior to sending traffic to the
public network and vice versa. Translation consists of replacing the IP address (NAT), port numbers (PAT), or
both, depending on the configuration.
While primarily deployed to translate private addresses to public addresses, NAT can translate from any
address to any other address, including public to public and private to private addresses.