ns1.popvertizerserving.net has no AAAA records.
Question and response
Question
dig ns1.popvertizerserving.net. AAAA
Answer
ns1.popvertizerserving.net. 5 CNAME popvertizerserving.net.
Authority
popvertizerserving.net. 3351 SOA ns-1510.awsdns-60.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0