How to completely clear all information on a PC about visiting the Internet?

Question

Browsers

History:
There is a PC with access to the Internet.
You cannot access the Internet on it (sites, games, porn, etc.)
"Check" comes, checks the PC and says: "You have used the Internet - this is prohibited!"
The man replies, "No, we didn't!" (lies)
1. What are the methods for checking a PC for "Internet access"?
Browser histories, cookies, ipconfig /displaydns|more and ......? (Interested without software)
2. What are the methods for completely cleaning a PC from traces of visiting the Internet?
ipconfig /flushdns, delete history, cookies and .... ? (interested without software)

Answer 1

The man replies, "No, we didn't!"

A person is shown the proxy log and screen shots taken by SMP :)

Answer 2

What are the methods for checking a PC for "Internet access"?

Gateway logs of course.
And if you need to clean it on the PC - the user profile and system logs.

Answer 3

The CCleaner program (there is a portable version so as not to leave any traces) will clean everything in general, including WindowsUpdate logs, which also arrive via the Internet. True, the updates themselves will remain. Restarting the computer will save you from ipconfig / displaydns. Well, that's all. And, no, non-standard programs also need to be deleted, probably. And where did they come from? And the directories of these programs in the %USERPROFILE%\AppData\Local directory and in the %USERPROFILE%\AppData\Roaming directory .

Answer 4

Read about "private browsing mode".
However, as already mentioned above, there are traces that remain not in the computer, but outside, at the provider.