[tzs]

This suggests an interesting question to put on an exam in whatever class teaches about Bloom filters.

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Q: It is proposed to make the local DNS resolver handle IPv4 by using 64 Bloom filters, BO1, BZ1, BO2, BZ2, ... BO64, BZ64.

Filter BOn answers the question "is bit n of the IP address a 1?", and BZn answers the question "is bit n of the IP address a 0?".

Your resolver checks all these Bloom filters. If BOn return "no", then it knows bit n of the address is 0. If BZn returns "no", then it is knows bit n of the address is a 1. Only if BOn and BZn both return "maybe" for some n must the resolver actually do a DNS query over the internet.

Explain why this proposed resolver would not be useful.

[maxfan8]

These would have to be pretty large and updated regularly. Why not use as k-anonymity scheme? A decent amount of password managers use that to see if the password a user generated is unique.