_s0.caltech.edu has no CNAME records.
Question and response
Question
dig _s0.caltech.edu. NS
Answer
The response has no answer records.
Authority
caltech.edu. 900 SOA ns0090.secondary.cloudflare.com. hostmaster.caltech.edu. 2022897825 10800 3600 2592000 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0