Cisco CCNA (200-301)IP ServicesMedium
A network engineer is configuring a Cisco router for Network Address Translation (NAT) to allow internal users to access the internet. They want to translate multiple internal private IP addresses to a single public IP address using port numbers. Which type of NAT is being configured?
- AOne-to-one NAT
- BPAT (Port Address Translation)
- CDynamic NAT
- DStatic NAT
Show answer & explanationAnswer & explanation
Correct answer: B. PAT (Port Address Translation)
Port Address Translation (PAT), also known as NAT Overload, is a type of NAT that translates multiple private IP addresses to a single public IP address by using different port numbers. This is the most common form of NAT used for internet access in small to medium-sized networks.
Why the other options are wrong
- A. One-to-one NAT is another term for Static NAT, mapping a single private to a single public IP.
- C. Dynamic NAT maps multiple private IPs to multiple public IPs from a pool, but without using port numbers to distinguish sessions.
- D. Static NAT maps a single private IP to a single public IP address permanently.
Port Address Translation (PAT)
PAT, or NAT Overload, allows multiple internal private IP addresses to share a single public IP address for external communication by differentiating connections based on source port numbers.
- Translates many-to-one (many private IPs to one public IP).
- Uses source port numbers to keep track of sessions.
- Most common form of NAT for home and small business internet access.
- Also known as NAT Overload.
Memory trick: Static is one, Dynamic is many, PAT's the port party!