| 12.0.0.0/8 | BGP route | AS7018 AT&T Enterprises, LLC | — |
| 12.0.0.0/8 | WHOIS (ARIN) | AT&T Enterprises, LLC | US |
| 12.0.0.0/8 | ARIN assigned | — | US |
| 12.128.0.0/9 | BGP route | AS7018 AT&T Enterprises, LLC | — |
| 12.240.0.0/12 | BGP route | AS7018 AT&T Enterprises, LLC | — |
| 12.128.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | — |
| 12.139.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.194.0.0/16 | BGP route | AS8030 AT&T WorldNet | — |
| 12.202.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.203.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.205.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.206.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.208.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.212.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.215.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.216.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.219.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.223.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.224.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.225.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.226.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.227.0.0/16 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.194.0.0/17 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.129.64.0/18 | WHOIS (ARIN) | CERFnet | — |
| 12.129.192.0/18 | WHOIS (ARIN) | CERFnet | US |
| 12.130.0.0/18 | WHOIS (ARIN) | CERFnet | — |
| 12.194.128.0/18 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.194.192.0/18 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.205.64.0/18 | WHOIS (ARIN) | Liberty Mobile Puerto Rico Inc. | — |
| 12.240.0.0/18 | WHOIS (ARIN) | Mediacom Communications Corp | US |
| 12.253.0.0/18 | BGP route | AS8030 AT&T WorldNet | — |
| 12.130.96.0/19 | BGP route | AS4262 California Education and Research Federation Network | — |
| 12.130.96.0/19 | WHOIS (ARIN) | CERFnet | — |
| 12.132.224.0/19 | WHOIS (ARIN) | AT&T Services, Inc. | US |
| 12.136.32.0/19 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.187.128.0/19 | WHOIS (ARIN) | ATT INCS | US |
| 12.213.192.0/19 | WHOIS (ARIN) | Wild Blue Communications | US |
| 12.130.64.0/20 | WHOIS (ARIN) | CERFnet | — |
| 12.134.96.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.134.112.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.134.176.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.134.192.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.134.208.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.134.224.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.134.240.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.135.0.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.135.16.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.135.112.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.135.240.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.0.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.16.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.64.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.80.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.96.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.112.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.128.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.136.144.0/20 | WHOIS (ARIN) | AT&T Worldnet Services | US |
| 12.152.144.0/20 | BGP route | AS33176 DTC Cable | — |
| 12.153.192.0/20 | BGP route | AS17253 TEC of Jackson, Inc. | — |
| 12.204.192.0/20 | BGP route | AS19957 AT&T Enterprises, LLC | — |
| 12.204.208.0/20 | BGP route | AS19957 AT&T Enterprises, LLC | — |
| 12.205.80.0/20 | BGP route | AS11992 Liberty Mobile Puerto Rico Inc. | — |
| 12.205.96.0/20 | BGP route | AS11992 Liberty Mobile Puerto Rico Inc. | — |
| 12.130.80.0/21 | BGP route | AS4264 California Education and Research Federation Network | — |
| 12.145.88.0/21 | BGP route | AS53768 Laboratory Corporation of America | — |
| 12.152.152.0/21 | BGP route | AS33176 DTC Cable | — |
| 12.154.104.0/21 | BGP route | AS2727 Electric Plant Board of the City of Glasgow, Kentucky | — |
| 12.160.128.0/21 | BGP route | AS14858 Hanson Information Systems, Inc. / Family Net | — |
| 12.161.104.0/21 | BGP route | AS25648 Parallax Systems | — |
| 12.163.16.0/21 | BGP route | AS17166 Travelers Property Casualty Corp. | — |
| 12.166.216.0/21 | BGP route | AS25921 LUS Fiber | — |
| 12.187.160.0/21 | BGP route | AS4917 AMDOCS Inc. | — |
| 12.204.216.0/21 | BGP route | AS19957 AT&T Enterprises, LLC | — |
| 12.133.120.0/22 | BGP route | AS27482 American Eagle Computer Products, Inc. | — |
| 12.148.180.0/22 | BGP route | AS14379 The Northern Trust Company | — |
| 12.157.188.0/22 | BGP route | AS11463 Kindred Healthcare, Inc. | — |
| 12.159.148.0/22 | BGP route | AS109 CISCO SYSTEMS, INC. | — |
| 12.166.196.0/22 | BGP route | AS11966 GLOBAL DATA SYSTEMS INC. | — |
| 12.166.208.0/22 | BGP route | AS25921 LUS Fiber | — |
| 12.171.228.0/22 | BGP route | AS40098 Community Antenna Service, Inc. | — |
| 12.171.232.0/22 | BGP route | AS40098 Community Antenna Service, Inc. | — |
| 12.171.244.0/22 | BGP route | AS27202 City of Bardstown, Kentucky | — |
| 12.172.116.0/22 | BGP route | AS27202 City of Bardstown, Kentucky | — |
| 12.172.164.0/22 | BGP route | AS394867 Velocity Communications, Inc. | — |
| 12.172.228.0/22 | BGP route | AS27202 City of Bardstown, Kentucky | — |
| 12.176.100.0/22 | BGP route | AS25648 Parallax Systems | — |
| 12.180.92.0/22 | BGP route | AS401694 Cloud 9 Wireless LLC | — |
| 12.193.244.0/22 | BGP route | AS2386 AT&T Enterprises, LLC | — |
| 12.205.248.0/22 | BGP route | AS30091 Access Cable Television, Inc. | — |
| 12.206.120.0/22 | BGP route | AS401694 Cloud 9 Wireless LLC | — |
| 12.208.120.0/22 | BGP route | AS62620 THE IRVINE COMPANY LLC | — |
| 12.215.20.0/22 | BGP route | AS27202 City of Bardstown, Kentucky | — |
| 12.216.8.0/22 | BGP route | AS2386 AT&T Enterprises, LLC | — |
| 12.216.12.0/22 | BGP route | AS2386 AT&T Enterprises, LLC | — |
| 12.221.116.0/22 | BGP route | AS2386 AT&T Enterprises, LLC | — |
| 12.221.136.0/22 | BGP route | AS54638 NETSOURCE ONE, INC | — |
| 12.221.212.0/22 | BGP route | AS2386 AT&T Enterprises, LLC | — |
| 12.222.200.0/22 | BGP route | AS40805 JMF Solutions, Inc | — |
| 12.236.84.0/22 | BGP route | AS2386 AT&T Enterprises, LLC | — |
| 12.237.4.0/22 | BGP route | AS26311 Ranch WiFi LLC | — |
| 12.239.120.0/22 | BGP route | AS40885 E2open LLC | — |