This CCNA tutorial describes the various types of NAT (network address translation) you need to know for the CCNA and for your career as a network engineer beyond the CCNA. These are relatively basic concepts you definitely need to know if you want to become an effective network engineer. In this CCNA tutorial, we will evaluate 3 methods of doing NAT routing traffic from an internal network to the internet:
- Static NAT – This is the simplest and more straightforward type of NAT and is also the most restrictive. A static NAT defines a one to one mapping between an internal and external IP address. The advantages of using a static NAT is that it is very easy to set up and few things can go wrong when you are configuring a static NAT. The disadvantage is that this method requires a global IP address for every NAT entry which might not be possible (or may be very expensive) especially if you are routing to the internet.
- Dynamic NAT (without PAT) – This defines a mapping between internal addresses and a pool of external addresses. This is similar to the static NAT, however, instead of one external address to map to, there are now several. This is a more flexible configuration, however, this might be an expensive solution due to the cost of internet IP addresses.
- Port Address Translation (PAT) – This defines a mapping between many internal addresses and one external IP address. In this case, many internal addresses can share 1 external IP address and this is a cost effective means doing network address translation. PAT can also be configured with a pool of external IP addresses for maximum flexibility.
I hope this CCNA tutorial has helped increase your knowledge on network address translation.