Monthly Archives: May 2013

Why more spam seen for OVH with v2 rankings than v1?

OVH Systems’ AS 16276 is #1 in the April 2013 worldwide from CBL data with 631,539,742 spam message seen according to the new Version 2 of, while the same ASN is #3 in the old version 1 rankings with 363,884,989 spam messages seen. Why the difference?

The difference is because Version 2 finds more netblocks assigned to AS 16276. Specifically:

72netblocks currently assigned
27netblocks previously assigned
14netblocks are persistant
58netblocks have been added
13netblocks have been removed

Many more netblocks were found for AS 16276 only by Version 2 than were found only by Version. So the difference in the amount of spam presumably comes from those added netblocks. Yes, we can drill down and see, and we may do that later.


Version 2 of

The April 2013 rankings include version 2 of the volume compilation method, with precise counts, resulting in slightly different ranking orders.

Top 3, April 2013 World from CBL data

For example, OVH, Hanaro, and Strato are the top three in both v1 and v2, but in a different order, in the April 2013 worldwide from CBL data.

Initially, we are only pubishing v2 for March and April 2013. In a few weeks we will publish the rest of the historical v2 rankings back to match the same months as the v1 rankings. Old v1 rankings will be kept online indefinitely for comparison, but all new rankings will be v2.