What is the "whois" requests limit?
I need to do a few thousands whois requests, I am pretty sure I will reach a limit at one point but I can't find exactly where that limit is, "man whois" shows me "No manual entry for whois".
Does someone knows how many whois requests I can do before reaching the limit?
11 Answer
There are different servers from all of the top level domain name managers, each with different limits. Furthermore, many of those managing entities change the limits in relation to current load on their servers. Some of them append a bit of time to your ban for every denied request, some don't. It's just really hard to say.
Some of the whois servers, like whois.iana.org (which holds information on all of the top level names, such as "net" and "org"), don't limit connections at all. The German one, I'm told, starts complaining after a few million requests. Some of the servers that are responsible for less well known top level names may block your access after only a few hundred requests.
If you do reach a limit and get blocked, it isn't the end of the world. You either have to wait for your ban to be lifted, or - if applicable - for your IP address to change. I would guess that a few thousand should be fine.
Maybe you'll want to put a 200ms delay between the requests, so they're spaced out over a few minutes.
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