Correct analysis of a large ip range?

Question

Python

In general, there is a need to find available proxy addresses in a particular (large) city.
The current approach is to take the known ranges for a given city under the http/socks4/socks5 types (yes, because of aiohttp) and also send requests in the form of a head to the target site (their load will not drop where it is not small). We also analyze the 5 most used ports for each type of proxy (there is a base for 10,000 proxies).
How can the amount of transmitted data be reduced?
Is there a chance that the server will return a response but not the site that is being requested?
How to check that the proxy has changed the ip address to its own?

Answer 1

Is there a chance that the server will return a response but not the site that is being requested?

yes, but there will be the IP of the responder, it must be different from the site,

How to check that the proxy has changed the ip address to its own?

proxyjudge and simpler checkers