53.48.139.199.in-addr.arpa.
Question and response
Question
dig mailproxy1.usda.gov. PTR
Answer
mailproxy1.usda.gov. 86400 PTR 53.48.139.199.in-addr.arpa.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0