IPv4-Mapped IPv6 Addresses Explained
Mapped addresses let IPv6 systems refer to IPv4 hosts. This guide explains the ::ffff: form and when it is used.
What is the IPv4 to IPv6 Converter?
IPv6 addresses can carry an old IPv4 address inside them, written as ::ffff: followed by the familiar dotted IPv4 address. This mapped form is used when IPv6 software needs to talk to an IPv4 host. This tool checks that the input is a valid IPv4 address, with four numbers from 0 to 255 separated by dots, and then shows the mapped form. It does not convert an address to a full native IPv6 address, which would need a different mapping.
How to use it
- Enter an IPv4 address in dotted form.
- Check that each of the four numbers is between 0 and 255.
- Press Convert to see the mapped IPv6 form.
Worked example
192.168.1.1 converts to the IPv4-mapped IPv6 form ::ffff:192.168.1.1.
What is the IPv6 form of 192.168.1.1?
Its IPv4-mapped IPv6 form is ::ffff:192.168.1.1.
Frequently asked questions
Is the mapped form a real IPv6 address?
It is a valid IPv6 format, but it represents an IPv4 host rather than a native IPv6 host. Software that understands mapped addresses uses it to bridge the two.
Why is 256 rejected?
Each part of an IPv4 address is a single byte, so it can only hold values from 0 to 255. Anything larger is not a valid IPv4 address.