Yes, definitely Comcast-wide. And I should have realized that was almost certainly true earlier. I did look at the Comcast looking glass listed at PeeringDB and even saw the problem, but didn't put 2-and-2 together at the time. All I saw was that the path for the IPv4 prefix for m-root, 202.12.27.0/24, matched the IPv6 prefix, 2001:dc3::/32, and the origin was WIDE Project, AS7500

RP/0/RSP0/CPU0:route-server.newyork.ny.ibone#show bgp 202.12.27.0/24

Mon Aug 26 05:12:03.793 utc

BGP routing table entry for 202.12.27.0/24

Versions:

  Process           bRIB/RIB  SendTblVer

  Speaker         1100876456  1100876456

Last Modified: May  6 23:17:18.578 for 3y16w

Paths: (1 available, best #1)

  Not advertised to any peer

  Path #1: Received by speaker 0

  Not advertised to any peer

  3257 7500, (aggregated by 7500 202.12.27.167), (received & used)

    66.208.229.9 from 66.208.229.9 (96.109.22.227)

      Origin IGP, metric 0, localpref 250, valid, internal, atomic-aggregate, best, group-best

      Received Path ID 0, Local Path ID 0, version 1100876456

      Community: 7922:403 7922:3000

      Originator: 96.109.22.227, Cluster list: 96.109.22.250, 96.109.22.50


RP/0/RSP0/CPU0:route-server.newyork.ny.ibone#show bgp ipv6 unicast 2001:dc3::/32

Mon Aug 26 05:14:43.682 utc

BGP routing table entry for 2001:dc3::/32

Versions:

  Process           bRIB/RIB  SendTblVer

  Speaker          873076831   873076831

Last Modified: May  6 23:15:42.581 for 3y16w

Paths: (1 available, best #1)

  Not advertised to any peer

  Path #1: Received by speaker 0

  Not advertised to any peer

  3257 7500, (aggregated by 7500 202.12.27.167)

    2001:559::9 from 2001:559::9 (96.109.22.227)

      Origin IGP, metric 0, localpref 250, valid, internal, atomic-aggregate, best, group-best

      Received Path ID 0, Local Path ID 0, version 873076831

      Community: 7922:403 7922:3000

      Originator: 96.109.22.227, Cluster list: 96.109.22.250, 96.109.22.50


But there's a /32 route for m.root-servers.net itself,

RP/0/RSP0/CPU0:route-server.newyork.ny.ibone#show bgp 202.12.27.33 

Mon Aug 26 05:10:50.040 utc

BGP routing table entry for 202.12.27.33/32

Versions:

  Process           bRIB/RIB  SendTblVer

  Speaker          918848884   918848884

Last Modified: Jun 18 02:40:28.576 for 3y10w

Paths: (1 available, best #1, not advertised to EBGP peer)

  Not advertised to any peer

  Path #1: Received by speaker 0

  Not advertised to any peer

  64650, (received & used)

    66.208.229.9 from 66.208.229.9 (96.109.22.250)

      Origin IGP, metric 0, localpref 300, valid, internal, best, group-best

      Received Path ID 0, Local Path ID 0, version 918848884

      Community: 7922:403 7922:2900 no-export


Which is a private AS number. Looks like Comcast is blackholing m-root?


I honestly can't imagine trying to explain this to frontline Xfinify support. Any Comcast lurkers around who might be able see what's going on here?