ns4.ti.com has no CNAME records.
Question and response
Question
dig ns4.ti.com. NS
Answer
The response has no answer records.
Authority
ti.com. 30 SOA oleibdm.itg.ti.com. hostmaster.ti.com. 2013108351 900 300 2419200 30
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0