smtp01.summitcommunications.net has no AAAA records.
Question and response
Question
dig smtp01.summitcommunications.net. AAAA
Answer
The response has no answer records.
Authority
summitcommunications.net. 3601 SOA pdns1.registrar-servers.com. hostmaster.registrar-servers.com. 1772542154 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0