This question already has an answer here:
ifconfig shows only one loopback address 127.0.0.1 and that it is assigned to network interface
ping 127.0.0.2 can receive packets back, even though
127.0.0.2 is not assigned to a (virtual) network interface.
Does a loop back IP address not need to be assigned to a network interface, in order to communicate with?
If no, why is 127.0.0.1 assigned to a virtual network interface
lo, if it doesn't need to be assigned in order to work?
Some said at https://unix.stackexchange.com/questions/507980/why-is-some-virtual-network-interface-assigned-private-ip-address-while-some-is#comment938403_507987
lo gets an IP address assigned to it so that packets sent from it have a source IP address
What does that mean?