Können Domainbesetzer erkennen, wann die Leute WHOIS-Anfragen stellen?

I have always used whois domain.com to check for information about domains, but this Stack Exchange question made me stop and think:

How do I check that a domain is available without triggering a grabber?

Can domain squatters actually detect when WHOIS requests are made?

Generally, no. You will notice that in the comments of the Stack Exchange question you linked to, we discovered that it was done through a web interface to WHOIS. The web interface was the “gotcha” element, and it was not the WHOIS query that was pinched, but it was a kind of man-in-the-middle attack where the “web->WHOIS interface” was used to hijack the request. When making a WHOIS request, use a trusted WHOIS client directly, not a web interface, and you should be OK.

I answered “Generally, no.” because it is conceivable that a registrar has been hacked or is in league with the bad guys, and you would not necessarily know about it. This is unlikely for most decent domains though. It is also possible (but again, unlikely) that your ISP is in on it and is sniffing the WHOIS requests through traffic since these requests are not encrypted.

For what it is worth, I have never had a domain name registered out from under me as a result of making a WHOIS request (through the use of a standard Linux WHOIS client).