Question and response
Question
dig ns2.dujiangyanren.com. DS
Answer
ns2.dujiangyanren.com. 5 CNAME dujiangyanren.com.
Authority
com. 900 SOA a.gtld-servers.net. nstld.verisign-grs.com. 1772782581 1800 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0