[Arthur Wildfire! March]

Thank you for the time.

What happens if two entities are registered with the same domain name/IP address?

What is the safeguard?

[jjotto]

Not hard at all for software to ID differences in the sites and ask the user. Straightforward nefarious spoofing is trickier though.

[palmer]

The safeguard against two people or companies registering the same domain is that the registrar does a who-is lookup for that TLD to see if the domain is already registered. I think there are still mixups but rare.

For IP addresses it is a lower level routing function. Like I said, the vast majority of domains have no unique IP or no IP whatsoever. To change that a domain owner logs into their registrar's website and then that website allows them to change their DNS settings to point to whatever IP they want. I can send any of my domains to any IP address that I feel like. What will happen on the other end depends on the SW on the other end.

A webserver will typically look at the incoming domain name and respond appropriately (with nothing in my case). But I should try pointing one of my domains to a google or bing address to see what happens.

Many many domains are pointed to single IPs which are running web servers configured to look at the incoming domain name (your browser always sends that along in the request). Then they look up the appropriate page for that domain name. That's how most ordinary people with domains can run their 10 or 100 or 10,000 domains all on one server with one IP. They might even share that server with other people with other domains. I do that at dreamhost.

I also have various servers at linode and digital ocean that each have their own IPV4 assigned and my domain on those hosts is the only one tied to that host. I have others with no domain tied to it and I access those via the IP address.