NAT for IPv4 Flashcards

Which NAT type allows multiple inside hosts to share a single public IP address using port numbers?

Answer: PAT (NAT Overload)

PAT (Port Address Translation), also called NAT Overload, maps multiple private IPs to a single public IP by tracking unique port numbers.

On a Cisco router, which command verifies active NAT translations in the translation table?

Answer: show ip nat translations

'show ip nat translations' displays the current entries in the NAT translation table including inside local, inside global, outside local, and outside global addresses.

What does the 'inside global' address represent in NAT terminology?

Answer: The public IP assigned to an internal host as seen from the outside

The inside global address is the translated (public) IP address that represents an internal host as seen from the outside network.

A router is configured with 'ip nat inside source list 10 interface GigabitEthernet0/0 overload'. What does 'overload' specify?

Answer: PAT using the interface's IP address

The 'overload' keyword enables PAT, and using 'interface' instead of a pool means the router's interface IP is used as the single public address.

Which command clears all dynamic NAT translations from the translation table?

Answer: clear ip nat translation *

'clear ip nat translation *' removes all dynamic NAT entries; static translations must be removed by deleting their configuration.

Which RFC defines the private IP address ranges commonly used behind NAT?

Answer: RFC 1918

RFC 1918 defines the three private address blocks: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

On a Cisco router, the interface facing the internal network should be configured with which NAT command?

Answer: ip nat inside

'ip nat inside' is applied to interfaces connected to the internal (private) network so the router knows which side hosts need translation.