The record route option is an option!

The IPv4 Record Route (RR) Option instructs routers to record their IP addresses in a packet. RR is subject to a nine hop limit and, traditionally, inconsistent support from routers. Recent changes in interdomain connectivity---the so-called "flattening Internet"---and new best practices for how routers should handle RR packets suggest that now is a good time to reassess the potential of the RR Option. We quantify the current utility of RR by issuing RR measurements from PlanetLab and M-Lab to every advertised BGP prefix. We find that 75% of addresses that respond to ping without RR also respond to ping with RR, and 66% of these RR-responsive addresses are within the nine hop limit of at least one vantage point. These numbers suggest the RR Option is a useful measurement primitive on today's Internet.