shell:$ nslookup -timeout=2 -retry=1 'ns-global-dual.rtc.vietteltammi.vn'
Server:		127.0.0.53
Address:	127.0.0.53#53

Non-authoritative answer:
ns-global-dual.rtc.vietteltammi.vn	canonical name = ns-global-dual-vn.rtc.vietteltammi.vn.
Name:	ns-global-dual-vn.rtc.vietteltammi.vn
Address: 125.212.219.201
Name:	ns-global-dual-vn.rtc.vietteltammi.vn
Address: 116.97.186.135