Found: One Troll

One of the projects I head at my day job is IP allocation and aggregation in order to keep our organization’s routing tables small and logical. As such, one of my responsibilities is to obtain new IP allocations from ARIN when we are running low on public address space. In the course of my obsession completely normal and healthy relationship with Sitemeter^[1], I’ve seen a lot of IP addresses run by, and it’s kind of a game I play to guess the age of the network.

For example, one of my regular readers has an IP address in a network that was only allocated to his ISP this year, which is adjacent to one of the class B networks we acquired late last year. There aren’t a whole lot of /8s or larger that ARIN allocates for use by end-user ISPs, so it’s fairly easy to spot the patterns if you’re used to looking at them. As far as I can tell, new allocations right now are coming from 173-174.x.x.x and 98-99.x.x.x. Early last year it was 66.0.0.0/8. Older networks begin with 12 (AT&T), 24, 67-76, and 96-97. These rules aren’t perfect, but that’s part of the fun. As ISPs shrink or switch to IPv6 (ha! right. . . ) they return their networks to ARIN and the networks get reallocated, so even though 72. and 24. addresses are generally older than dirt (in internet years), sometimes you get newly allocated ones popping up.

Governments and universities are hard to guess, but fun to research. One can spent a lot of time looking at the map of the internet. Part of the fun of checking into these things is that you can generally deduce that new allocations are growing markets, or new markets. If the IPs have been in one place for 10 years, you know that’s a stable market, and you can even guess the size of the market based on the size of its IP allocation.

Anyway, that’s one of my geeky pasttimes.

1. Joke shamelessly stolen from JayG [↩]