Cisco CCNA NAT for IPv4 2 — Questions and Answers
Question 1: Which NAT type allows multiple inside hosts to share a single public IP address using port numbers?
- Static NAT
- Dynamic NAT
- PAT (NAT Overload) (Correct answer)
- Policy NAT
Correct 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.
Question 2: On a Cisco router, which command verifies active NAT translations in the translation table?
- show ip nat statistics
- show ip nat translations (Correct answer)
- debug ip nat
- show running-config | include nat
Correct 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.
Question 3: What does the 'inside global' address represent in NAT terminology?
- The private IP of an internal host
- The public IP assigned to an internal host as seen from the outside (Correct answer)
- The public IP of an external server
- The private IP of an external host
Correct 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.
Question 4: A router is configured with 'ip nat inside source list 10 interface GigabitEthernet0/0 overload'. What does 'overload' specify?
- Static NAT mapping
- Dynamic NAT with a pool
- PAT using the interface's IP address (Correct answer)
- One-to-one NAT
Correct 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.
Question 5: Which command clears all dynamic NAT translations from the translation table?
- clear ip nat translation * (Correct answer)
- no ip nat translation
- clear ip nat statistics
- flush ip nat translations
Correct answer: clear ip nat translation *
'clear ip nat translation *' removes all dynamic NAT entries; static translations must be removed by deleting their configuration.
Question 6: Which RFC defines the private IP address ranges commonly used behind NAT?
- RFC 1918 (Correct answer)
- RFC 2460
- RFC 3022
- RFC 4271
Correct 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.
Question 7: On a Cisco router, the interface facing the internal network should be configured with which NAT command?
- ip nat outside
- ip nat inside (Correct answer)
- ip nat enable
- ip nat pool internal
Correct 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.
Cisco CCNA NAT for IPv4 2
Which NAT type allows multiple inside hosts to share a single public IP address using port numbers?