IPv4 vs IPv6

Purpose of IP Addresses and the Problem IPv6 Solves

An IP address (Internet Protocol address) is a numeric label to identify a network interface of a computer or network node participating in a computer network using the relevant IP version.

IPv6 was created to tackle the problem of IPv4 exhaustion.

IPv6 uses 128 bit addresses, yielding an address space of 2^128 possible addresses.   This contrasts massively with IPv4 which is only 32 bits!!

Why is there no Planned IPv7?

The address space of IPv6 is so large that address exhaustion is not a foreseen possibility, and hence no IPv7 is planned at present.

What transition technologies are in play to help move to IPv6?

There are some transition technologies e.g. NAT64, aimed at easing the transition from IPv4 to IPv6.

Apart from Bigger Address Space, what else does IPv6 Bring to the Table?

Apart from bigger size, IPv6 also adds some interesting new features. Learn these.

Understanding localhost

Everyone has used localhost. But few have explicitly thought about and written down what it really means. 

localhost is a reserved domain name that the OS maps to itself; typically 127.0.0.1 for IPv4 and ::1 for IPv6.

It bypasses DNS as requests to localhost never go out to the Internet. The OS resolves it internally.

Localhost traffic is routed through a virtual network interface that loops packets back into the machine without touching any physical network hardware.

Developers run local servers (e.g. localhost:3001) to test code quickly, safely and without exposing anything to the Internet.