gbThreads

[Stuart McLachlan]

So the minimal hosts file (out of the box) consists of just one single entry:

Code:

0.0.0.0 localhost

Bad practice.  ChatGPT explains it well:

Normally, no — you should not have a 0.0.0.0 localhost entry in your hosts file.

Here’s why:

Standard definition of localhost
By convention, localhost maps to 127.0.0.1 (IPv4) and ::1 (IPv6).
These are the loopback addresses that always point to the local machine.

What 0.0.0.0 means
0.0.0.0 is a special IPv4 address. It does not mean "this machine" in the same way as 127.0.0.1.
Instead, it usually means "all IPv4 addresses on this host" when binding a server, or "no valid address" in some contexts.
If you put 0.0.0.0 localhost, some software may fail because it expects localhost to resolve to a real loopback address.

Potential problems if you use it
Some programs (databases, development servers, etc.) check specifically for 127.0.0.1.
Redirecting localhost to 0.0.0.0 can break local connections, or make them listen on the wrong interface.
For example, ping localhost might fail.