EDIT: Looks like this might be an issue w/ my AT&T-provided CPE, sorry! (more details at the bottom)
From my vantage point, 1.1.1.1 is inaccessible, while 1.0.0.1 seems to work just fine.
Comments on the blog post blame this on "various reasons" but, at least in my case, this seems to be a Cloudflare issue:
$ ping -c 5 -q 1.0.0.1
PING 1.0.0.1 (1.0.0.1) 56(84) bytes of data.
--- 1.0.0.1 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4005ms
rtt min/avg/max/mdev = 34.955/35.737/37.492/0.936 ms
$ ping -c 5 -q 1.1.1.1
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
--- 1.1.1.1 ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4102ms
$ traceroute 1.0.0.1
traceroute to 1.0.0.1 (1.0.0.1), 30 hops max, 60 byte packets
[...]
3 * * *
4 12.83.79.61 (12.83.79.61) 28.126 ms 28.663 ms 29.110 ms
5 cgcil403igs.ip.att.net (12.122.132.121) 35.854 ms 37.532 ms 37.510 ms
6 ae16.cr7-chi1.ip4.gtt.net (173.241.128.29) 33.997 ms 29.083 ms 29.647 ms
7 xe-0-0-0.cr1-det1.ip4.gtt.net (89.149.128.74) 37.758 ms 35.165 ms 36.620 ms
8 cloudflare-gw.cr0-det1.ip4.gtt.net (69.174.23.26) 36.946 ms 37.343 ms 38.574 ms
9 1dot1dot1dot1.cloudflare-dns.com (1.0.0.1) 38.385 ms 36.621 ms 37.157 ms
$ traceroute 1.1.1.1
traceroute to 1.1.1.1 (1.1.1.1), 30 hops max, 60 byte packets
[...]
3 * * *
4 12.83.79.61 (12.83.79.61) 30.388 ms 12.83.79.41 (12.83.79.41) 30.601 ms 31.280 ms
5 cgcil403igs.ip.att.net (12.122.132.121) 37.602 ms 37.873 ms 37.808 ms
6 ae16.cr7-chi1.ip4.gtt.net (173.241.128.29) 33.441 ms 29.788 ms 29.678 ms
7 xe-0-0-0.cr1-det1.ip4.gtt.net (89.149.128.74) 35.266 ms 35.124 ms 33.921 ms
8 cloudflare-gw.cr0-det1.ip4.gtt.net (69.174.23.26) 35.294 ms 35.949 ms 35.455 ms
9 * * *
10 * * *
11 * * *
12 *^C
EDIT: I have AT&T-provided CPE that I have to use due to 802.1X. If I log into the device (over HTTP) and use the built-in (web-based) diagnostics tools, I am able to successfully ping 1.1.1.1 from the device itself:
ping successful: icmp seq:0, time=2.364 ms
ping successful: icmp seq:1, time=1.085 ms
ping successful: icmp seq:2, time=1.160 ms
ping successful: icmp seq:3, time=1.245 ms
ping successful: icmp seq:4, time=0.739 ms
When pinging 1.1.1.1 from my (pfSense-based) router sitting directly behind the modem, however, no replies come back from the modem to the router (confirmed via pcap on the upstream-facing interface).
Thus, it looks like this is an issue with the AT&T CPE (5268AC).
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