Apex domains cannot have CNAME records.
Question and response
Question
dig cis.strath.ac.uk. NS
Answer
cis.strath.ac.uk. 1 NS dns1.cis.strath.ac.uk.
cis.strath.ac.uk. 1 NS dns0.strath.ac.uk.
cis.strath.ac.uk. 1 NS dns0.cis.strath.ac.uk.
cis.strath.ac.uk. 1 NS dns2.cis.strath.ac.uk.
Authority
The response has no authority records.
Additional
dns0.cis.strath.ac.uk. 1 A 130.159.196.94
dns1.cis.strath.ac.uk. 1 A 130.159.196.93
dns2.cis.strath.ac.uk. 1 A 130.159.196.92
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0