Apex domains cannot have CNAME records.
Question and response
Question
dig reedelsevier.com. NS
Answer
reedelsevier.com. 5 NS ns2.lexisnexis.com.
reedelsevier.com. 5 NS ns3.lexisnexis.com.
reedelsevier.com. 5 NS ns4.lexisnexis.com.
reedelsevier.com. 5 NS ns1.lexis-nexis.com.
Authority
The response has no authority records.
Additional
ns1.lexis-nexis.com. 5 A 138.12.4.3
ns2.lexisnexis.com. 5 A 138.12.4.2
ns3.lexisnexis.com. 5 A 198.81.200.11
ns4.lexisnexis.com. 5 A 207.25.180.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0