1 |
On 3/10/21 9:38 AM, Michael wrote: |
2 |
> I always thought the localhost class A addresses were from days of old |
3 |
> 'inter- network' era. The difference with 127.0.0.1 and a private |
4 |
> LAN address is the 127.0.0.1 does not reach the data link layer, |
5 |
> but loops-back at IP layer 3 and responds to any applications on the |
6 |
> local PC. So, I understood this to mean it never went through the |
7 |
> whole network stack, as it does when you ping a remote host. |
8 |
|
9 |
The 127/8 (formerly called a class A) network is reserved / allocated |
10 |
for a host to communicate with itself. |
11 |
|
12 |
However, /how/ local addresses are used is entirely implementation |
13 |
specific. This goes for both 127.0.0.1 and other addresses bound to |
14 |
local network cards. |
15 |
|
16 |
Linux will not send traffic to the local LAN IP to the NIC either. But |
17 |
that's a /Linux/ /implementation/ detail. Other OSs, e.g. Windows, |
18 |
don't use a loopback adapter for 127.0.0.1. Instead it's purely a |
19 |
software construct. But that's a /Windows/ /implementation/ detail. |
20 |
|
21 |
Aside: Windows (2k and onward) does have a loopback adapter that you |
22 |
can optionally install. However you /can't/ assign 127.0.0.1 (or any |
23 |
127/8) to it. It is meant to be used like Linux uses the dummy adapter. |
24 |
|
25 |
|
26 |
|
27 |
-- |
28 |
Grant. . . . |
29 |
unix || die |