Found twitter.com was not loading tonight. Dug in. $ host www.twitter.com www.twitter.com is an alias for twitter.com. twitter.com has address 104.244.42.129 twitter.com mail is handled by 30 ASPMX2.GOOGLEMAIL.com. twitter.com mail is handled by 20 alt2.aspmx.l.google.com. twitter.com mail is handled by 20 alt1.aspmx.l.google.com. twitter.com mail is handled by 10 aspmx.l.google.com. twitter.com mail is handled by 30 ASPMX3.GOOGLEMAIL.com. $ dig ns twitter.com +short b.r06.twtrdns.net. a.r06.twtrdns.net. c.r06.twtrdns.net. d.r06.twtrdns.net. a.u06.twtrdns.net. b.u06.twtrdns.net. c.u06.twtrdns.net. d.u06.twtrdns.net. $ dig @b.r06.twtrdns.net a twitter.com +short 104.244.42.129 And 104.244.42.129 does indeed point to Twitter (per WHOIS/ARIN), so doesn't appear to be a DNS-related thing. Onward we go: $ mtr www.twitter.com Packets Pings Host Loss% Snt Rcv Last Avg Best Wrst 1. 192.168.1.254 0.0% 9 9 0.6 0.6 0.5 0.8 2. 172-10-232-1.lightspeed.sntcca.sbcglobal.net (172.10.232.1) 0.0% 9 9 2.3 2.3 1.5 4.3 3. 71.148.149.42 (71.148.149.42) 0.0% 8 8 2.6 2.7 1.7 3.9 4. 12.242.117.22 (12.242.117.22) 0.0% 8 8 4.6 6.1 3.6 8.2 5. att-gw.sfo.pccw.net (192.205.32.82) 0.0% 8 8 6.7 6.5 5.3 8.1 6. Bundle-Ether45.br04.osa01.pccwbtn.net (63.223.26.30) 0.0% 8 8 121.6 121.1 119.6 122.8 7. 63-222-51-222.static.pccwglobal.net (63.222.51.222) 0.0% 8 8 154.3 154.4 153.3 155.8 8. (waiting for reply) 9. 104.244.42.129 (104.244.42.129) 0.0% 8 8 151.5 152.6 151.4 153.8 $ mtr -z www.twitter.com Packets Pings Host Loss% Snt Rcv Last Avg Best Wrst 1. AS??? 192.168.1.254 0.0% 8 8 0.8 0.6 0.3 0.8 2. AS7018 172-10-232-1.lightspeed.sntcca.sbcglobal.net (172.10.2 0.0% 8 8 1.3 2.2 1.0 4.1 3. AS7018 71.148.149.42 (71.148.149.42) 0.0% 8 8 2.2 3.4 1.9 5.0 4. AS7018 12.242.117.22 (12.242.117.22) 0.0% 8 8 6.0 6.1 4.5 7.6 5. AS7018 att-gw.sfo.pccw.net (192.205.32.82) 0.0% 8 8 5.6 6.2 4.8 7.7 6. AS3491 Bundle-Ether45.br04.osa01.pccwbtn.net (63.223.26.30) 0.0% 8 8 120.4 120.7 120.0 121.5 7. AS3491 63-222-51-222.static.pccwglobal.net (63.222.51.222) 0.0% 8 8 154.1 155.4 153.6 161.5 8. (waiting for reply) 9. AS13414 104.244.42.129 (104.244.42.129) 0.0% 7 7 152.7 152.2 150.8 154.0 AS3491 (pccwbtn.net) is PCCW Global, though a WHOIS on pccwbtn.net says they're PCCW-HKT out of Hong Kong, which would explains the huge jump in latency (6ms -> 121ms) since I'm located in California. 63.223.26.30 is also PCCW Global. PeeringDB says https://www.peeringdb.com/net/674 (AT&T) has a looking glass server at http://route-server.ip.att.net/ but the webserver is not listening on TCP port 80, nor 443: $ telnet route-server.ip.att.net 80 Trying 12.0.1.28... telnet: connect to address 12.0.1.28: Connection refused telnet: Unable to connect to remote host $ telnet route-server.ip.att.net 443 Trying 12.0.1.28... telnet: connect to address 12.0.1.28: Connection refused telnet: Unable to connect to remote host And for those that want source and destinations: src IP: 107.197.104.143 (AT&T Fibre) dst IP: 104.244.42.129 (Twitter) -- | Jeremy Chadwick jdc_at_koitsu.org | | UNIX Systems Administrator PGP 0x2A389531 | | Making life hard for others since 1977. |