xip.io welcome screens says this :
10.0.0.1.xip.io resolves to 10.0.0.1
Why do we need to go through xip io when I can directly use the IP?
Is it used to access servers by domain name instead of IP?
The main use case is when your application needs to support multiple subdomains.
Take for example these production subdomains:
- www.example.com
- admin.example.com
- members.example.com
Or you can consider a multi-tenant application where each account gets its own custom subdomain:
- mycompany.example.com
- anotherguy.example.com
So it's easy enough to setup a production environment to serve this requests.
But without a service like xip.io for your development environment, you cannot put a subdomain in front of an IP address to route your request appropriately.
To get around this, you can access your application through a subdomain like this through xip.io:
http://mycompany.10.0.0.1.xip.io/
As xip.io states, this then works flawlessly if you're trying to access the application from other machines on your local network, be they smartphones, tablets, other OSes within VMs, etc.
来源：https://stackoverflow.com/questions/37150895/why-is-xip-io-needed-when-i-can-access-the-ip-directly