Cisco CCNA NAT for IPv4 3

Question 1

Which NAT address term describes the IP address of an external host as seen from the inside network?

Accepted Answer

Outside local

Answer

The outside local address is how an external host's IP appears to the inside network, which may differ from its true public IP if destination NAT is used.

Question 2

A PAT table has exhausted all available port numbers for a given public IP. What happens to new connection attempts?

Accepted Answer

New translations fail and connections are dropped

Answer

When all ~65,535 ports are in use for a PAT address, no new translations can be created and new connections from inside hosts are dropped.

Question 3

Which statement correctly distinguishes Dynamic NAT from PAT?

Accepted Answer

Dynamic NAT maps one private IP to one available pool address; PAT maps many private IPs to one address using ports

Answer

Dynamic NAT creates a one-to-one mapping from a pool of public IPs; PAT maps multiple private IPs to a single public IP distinguished by unique port numbers.

Question 4

Which protocol does NAT handle differently because it has no port number in its header?

Accepted Answer

ICMP

Answer

ICMP lacks TCP/UDP port numbers, so PAT uses the ICMP query identifier field to differentiate multiple inside hosts sharing one public IP.

Question 5

What is the maximum number of simultaneous PAT translations theoretically possible per public IP address?

Accepted Answer

65,535

Answer

PAT can theoretically support up to 65,535 simultaneous translations per public IP address, one per unique port number in the valid port range.

Cisco CCNA Practice Test

Cisco CCNA Practice Test

Cisco CCNA NAT for IPv4 3