a2.verisigndns.com has no NS records.
NS records for this zone are defined at verisigndns.com.
NS records for this zone are defined at verisigndns.com.
Question and response
Question
dig a2.verisigndns.com. NS
Answer
The response has no answer records.
Authority
verisigndns.com. 86400 SOA av1.nstld.com. dnssupport.verisign-grs.com. 1772669970 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0