问题
What is the difference between these two variables?
REMOTE_HOST and REMOTE_ADDR.
回答1:
REMOTE_HOST pertains to the hostname of the client (i.e. the computer making the request). REMOTE_ADDR refers to the IP address of the client.
There would be times when the hostname is unresolvable so the REMOTE_HOST will return the REMOTE_ADDR or the IP address instead.
回答2:
1. $_SERVER['REMOTE_ADDR'] -
This contains the real IP address of the client. That is the most reliable value you can find from the user.
2. $_SERVER['REMOTE_HOST'] -
This will fetch the Host name from which the user is viewing the current page.
But for this script to work, Hostname Lookups On inside httpd.conf must be configured.
回答3:
Remote: is a computer that resides in some distant location from which data retrieved it typically refer to a server in a private network or the public internet.
Remote_ host will return the REMOTE_ ADDR Or the IP address instead .
来源：https://stackoverflow.com/questions/3812166/difference-between-remote-host-and-remote-addr