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?