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.