I did a little experiment yesterday. I fetched the entire ripe.db.route file from the ripe.net FTP server and for each route specified in that file (a total of 245,890 routes) I extracted the base IPv4 address of the route and then looked that address up within the asn.routeviews.org DNS zone, which is kindly provided by the Routeviews Project at the Advanced Network Technology Center at the University of Oregon. That DNS zone allows users to quickly find the _actual_ route and ASN that is currently associated with any given IPv4 address.
The results of my little experiment are simple to summarize. 10,829 of the base addresses listed in the ripe.db.route file are not actually being routed at the present time (at least they weren't, yesterday, at the time I ran this analysis). Of the remaining 235,061 route base IP addresses, fully 28,988 of those (12.3%) are being announced by some AS other than the one specified in the ripe.db.route file. My results file is available here: ftp://ftp.tristatelogic.com/pub/ripe.db.route.routecheck In that file, any line containing only one field -is- being routed and -is- being routed by the AS specified in the ripe.db.route file. Lines in the results file with contain exactly two whitspace separated fields are not currently being routed. Lines in the results file that contain exactly three whitspace separated fields are being routed by some AS other than the one called for within the ripe.db.route file. In these cases, field #1 is the route from the ripe.db.route file, field #2 is the AS number from the ripe.db.route file, and field #3 is the ASN that is _actually_ routing the base IP address at the present time (as of yesterday). Given the considerable number of routing anomalies revealed by my simple experiment, I am inclined to wonder who is actually using all of that route information in the RIPE DB, and what on earth they could be using it for. If anyone could enlighten me on this point, I would appreciate it.
