What is the difference between a public IP, a private IP and NAT?
Options
- Public IPs reach the internet; private IPs stay inside; NAT translates (Correct option)
- They are identical and differ only in the way they are written
- Private IPs are faster than public IPs in every network
- NAT encrypts the data that goes through the router
Answer
Public IPs are reachable from the internet; private IPs (10.x, 172.16-31.x, 192.168.x) are only used inside a network; NAT lets private hosts reach the internet by translating to a public address
Why
Private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) are not routed on the public internet; many networks reuse them.
A NAT gateway translates the private source address of outgoing traffic into a public address, and maps replies back. So servers in a private subnet can download updates, but outsiders cannot start connections to them.
Remember
Private inside, public outside, NAT translates.