For analytics purposes, I'm looking at large sets of IP addresses in server log files. I'm trying to perform reverse-DNS lookups to understand where traffic is coming from - e.g. what percentage of IPs resolve to corporations, schools, government, international etc.
Despite a bunch of optimizations, individually reverse-DNS'ing every IP address still appears to be fairly expensive though. So -
is there any way to obtain an entire range of IPs from a reverse-DNS?
If yes, this could greatly reduce the number of actual reverse-DNS lookups.
Example (numbers slightly obfuscated):
- Log file contains a request from an IP
- Reverse DNS resolves to
126.96.36.199.in-addr.arpa 21599 IN PTR alamo.ceas.rochester.edu
- (So this is a visitor from Rochester University, rochester.edu)
- Now, would it be safe to assume that all at least all IPs from
128.151.162.*will also resolve to rochester.edu?
- What about
128.151.*.*? Is there a way to get the exact IP range?