Often in the course of troubleshooting network issues, we'll encounter events which occur at regular, predictable intervals. For example, suppose a routing adjacency fails every three minutes almost exactly. The goal then becomes to consider what events occur or what limits are reached along that same interval; what happens every three minutes?
It occurred to me recently that as often as this is the case in troubleshooting, I was not aware of any master list compiled of all such suspect events and timers. So, I started one: a wiki page titled Well-known Intervals.
The wiki page is intended to serve as a list of events which happen at predictable intervals to help while troubleshooting specific issues. I've seeded the list with a few dozen things I could think of, but there is of course plenty of room for expansion.
If you find the list useful, please consider helping to expand it with additional events you think of or encounter in the field.