mail-gw.firsthost.lv has no CNAME records.
Question and response
Question
dig mail-gw.firsthost.lv. NS
Answer
The response has no answer records.
Authority
firsthost.lv. 1672 SOA joaquin.ns.cloudflare.com. dns.cloudflare.com. 2398254556 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0