Apex domains cannot have CNAME records.
Question and response
Question
dig lightspeed.gnvlsc.sbcglobal.net. NS
Answer
lightspeed.gnvlsc.sbcglobal.net. 3 NS ns3.attdns.com.
lightspeed.gnvlsc.sbcglobal.net. 3 NS ns4.attdns.com.
lightspeed.gnvlsc.sbcglobal.net. 3 NS ns1.attdns.com.
lightspeed.gnvlsc.sbcglobal.net. 3 NS ns2.attdns.com.
Authority
The response has no authority records.
Additional
ns1.attdns.com. 2 A 144.160.112.22
ns2.attdns.com. 2 A 144.160.128.140
ns3.attdns.com. 2 A 144.160.20.47
ns4.attdns.com. 2 A 144.160.229.11
ns1.attdns.com. 2 AAAA 2001:1890:1286:320:0:0:c:2
ns2.attdns.com. 2 AAAA 2001:1890:1c00:3320:0:0:c:3
ns3.attdns.com. 2 AAAA 2001:1890:1c00:5323:0:0:c:3
ns4.attdns.com. 2 AAAA 2001:1890:1c00:6320:0:0:c:6
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0