100-150 Question 68
Select 2A small business has been assigned the public IP address range 203.0.113.0/24 but wants to conserve public IP addresses while allowing multiple devices on their private network to access the internet. They have decided to use Network Address Translation (NAT). Which IP address ranges are valid for their private network, and which NAT type should they implement?
- A
10.0.0.0/8 and Dynamic NAT
- B
192.168.0.0/16 and Static NAT
- C
172.16.0.0/12 and Port Address Translation (PAT)
- D
203.0.113.0/24 and Dynamic NAT
- E
192.0.2.0/24 and Port Address Translation (PAT)
Show answer and explanation
Correct answers: A, C
Explanation
Private IP ranges (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) are used in conjunction with NAT to allow internal devices to access external networks. Dynamic NAT maps private IPs to a pool of public IPs, while PAT (a type of NAT) enables multiple private IPs to share a single public IP using unique port numbers. The most efficient combination for conserving public IPs in this scenario is using a private IP range like 10.0.0.0/8 or 172.16.0.0/12 with PAT.
- A. Correct.
10.0.0.0/8 is a valid private IP range as defined by RFC 1918, and Dynamic NAT is suitable for mapping private IP addresses to a pool of public IP addresses.
- B. Incorrect.
192.168.0.0/16 is a valid private IP range, but Static NAT maps one private IP to one public IP and does not conserve public addresses effectively.
- C. Correct.
172.16.0.0/12 is a valid private IP range as per RFC 1918, and Port Address Translation (PAT) allows multiple private IPs to share a single public IP by using different port numbers, making it efficient for conserving public IP addresses.
- D. Incorrect.
203.0.113.0/24 is a public IP range, not a private range, and is not valid for internal private network addressing. Dynamic NAT is also not the most efficient method for conserving public IP addresses.
- E. Incorrect.
192.0.2.0/24 is a reserved IP range for documentation and examples, not a private range, and cannot be used for internal addressing. Port Address Translation (PAT) requires valid private IPs to function.