IPv6 Functionality

Registry value and comments

Prefer IPv4 over IPv6

Dec 32
Hex 0x20
Bin xx1x xxxx

Recommended instead of disabling IPv6.

Disable IPv6

Dec 255
Hex 0xFF
Bin 1111 1111

See startup delay occurs after you disable IPv6 in Windows

if you encounter startup delay after disabling IPv6 in Windows 7 SP1 or Windows Server 2008 R2 SP1.

Additionally, system startup will be delayed for five seconds if IPv6 is disabled by incorrectly, setting the DisabledComponents registry setting to a value of 0xffffffff. The correct value should be 0xff. For more information, see Internet Protocol Version 6 (IPv6) Overview

.

The DisabledComponents registry value doesn't affect the state of the check box. Even if the DisabledComponents registry key is set to disable IPv6, the check box in the Networking tab for each interface can be checked. This is an expected behavior.

You cannot completely disable IPv6 as IPv6 is used internally on the system for many TCPIP tasks. For example, you will still be able to run ping ::1

after configuring this setting.

Disable IPv6 on all nontunnel interfaces

Dec 16
Hex 0x10
Bin xxx1 xxxx

Disable IPv6 on all tunnel interfaces

Dec 1
Hex 0x01
Bin xxxx xxx1

Disable IPv6 on all nontunnel interfaces (except the loopback) and on IPv6 tunnel interface

Dec 17
Hex 0x11
Bin xxx1 xxx1

Prefer IPv6 over IPv4

Bin xx0x xxxx

Re-enable IPv6 on all nontunnel interfaces

Bin xxx0 xxxx

Re-enable IPv6 on all tunnel interfaces

Bin xxx xxx0

Re-enable IPv6 on nontunnel interfaces and on IPv6 tunnel interfaces

Bin xxx0 xxx0