b.ns.kth.se has no CNAME records.
Question and response
Question
dig b.ns.kth.se. NS
Answer
The response has no answer records.
Authority
kth.se. 414 SOA a.ns.kth.se. hostmaster.kth.se. 2026030419 14400 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0