mail.emtelco.com.co has no NS records.
NS records for this zone are defined at emtelco.com.co.
NS records for this zone are defined at emtelco.com.co.
Question and response
Question
dig mail.emtelco.com.co. NS
Answer
The response has no answer records.
Authority
emtelco.com.co. 1800 SOA jason.ns.cloudflare.com. dns.cloudflare.com. 2397462606 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0