Yup! I’m back. All I thought I won’t be writing blogs anymore. I’ve been busy filling more CCNA knowledge and experience. I even landed a CCNA related job as a provisioning engineer in an Australian telco. I’ve realized the need of CCNA basic knowledge during the interview. One out of almost networking foundation questions I encountered are these: What is private IP address? What is public IP address? What are their differences? I answered on how I interpret public and private literally and I feel very ashamed to the interviewer because my answer is definitely wrong. So here I am, who learned from mistakes trying to prove anyone that I’ve already learned the significance of private IPv4 address. Good thing, I excel on other questions and passed series of interviews.
Ok. Let’s be straight forward:
Public IP address–> routable to internet
Private IP address –> not routable to internet
The need of private IP address is that we can assign IP address to any device that does not need to be connected to internet.These are ip addresses like:
The first time I encountered these ip addresses especially 192.168.something is when I am trying to change the name of my Wi-Fi. When I entered the bootcamp, I eventually realized that it is the gateway of the router. So come to think of this, there are lots of devices in the world. A single average person has cellphone and tablet that connects to internet. Also business depends on either service laptops and desktops. If we going to assign an IP address to each devices, we will not have enough space for IP address. The need for classification of IP address and the concept of NAT is the solution for this problem. NAT refers to Network Address Translation or simply translating private IP address to public IP address and vice versa.
Network efficiency was achieved using this NAT concept, how it works?, I’ll discuss it on the separate NAT post. As a summary, the private IP addresses are used for communication that does not need Internet service. Also, the biggest advantage of private IP address is that public IP addresses are costly. Public IP addresses are only bought by telco or ISP of course those are institutes which are good in IP management.