I have recently run into a discussion on this topic, and I think there is a need for some more detailed technical answer.
I want to ask this simple and basic question:
When I configure a service on an IP network host (http, ftp, dns, etc.), e.g. 10.0.0.11 and I access the service from the same host with the IP address of one network interface (not with 127.0.0.1 - loopback, but 10.0.0.11), is there any chance that the IP packets with the sourceIP=destinationIP=10.0.0.11 get anywhere beyond the local network interface?
(So when there is a problem with the switch or router it could cause my service ftp://10.0.0.11 (dns ...) to become unavailable from a browser running on 10.0.0.11)?