Difference between ping localhost and 127.0.0.1

[brian_mi]

Hey, does anyone could tell me the difference between ping localhost and ping 127.0.0.1?

I get different results from these two commands.

[zivan56]

localhost resolves to 127.0.0.1 on Windows. So you are bypassing the DNS subsystem when you ping the IP directly.

It may be different on Windows 7, where localhost resolves to an IPv6 address by default.

[gdodson]

If pinging localhost gives you replies from ::1, that's your IPv6 address where 127.0.0.1 is an IPv4 address.

[brian_mi]

Yes I'm trying on Win7 and i get ::1.

my further question is, why to resolve localhost to ipv6? what if i have Apache on my machine? it goes under ipv6?

[+BudMan MVC]

If your not using IPv6 -- you can just disable it.

reg add hklm\system\currentcontrolset\services\tcpip6\parameters /v DisabledComponents /t REG_DWORD /d 255

As you see my win 7 box does not resolve localhost to the ipv6 address

Microsoft Windows [Version 6.1.7600]

Copyright © 2009 Microsoft Corporation. All rights reserved.

C:\Windows\System32>ping localhost

Pinging quad-w7.local.lan [127.0.0.1] with 32 bytes of data:

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

[brian_mi]

If your not using IPv6 -- you can just disable it.

reg add hklm\system\currentcontrolset\services\tcpip6\parameters /v DisabledComponents /t REG_DWORD /d 255

As you see my win 7 box does not resolve localhost to the ipv6 address

Microsoft Windows [Version 6.1.7600]

Copyright © 2009 Microsoft Corporation. All rights reserved.

C:\Windows\System32>ping localhost

Pinging quad-w7.local.lan [127.0.0.1] with 32 bytes of data:

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

Thanks BudMan~~ :shifty:

[Fred Derf Veteran]

Presumably this was done with the expectation that by the end of Windows 7s life cycle that IPv6 addresses will be the norm or even required.

[The_Decryptor Veteran]

It's just the right thing to do if you have IPv6 enabled, it should try v6 first and fallback to v4 if it isn't possible.

Edit: It's so stuff like this works fine.

If you have v6 connectivity you should get the v6 address over the v4 one.