13.sucuridns.com has no NS records.
NS records for this zone are defined at sucuridns.com.
NS records for this zone are defined at sucuridns.com.
Question and response
Question
dig 13.sucuridns.com. NS
Answer
The response has no answer records.
Authority
sucuridns.com. 900 SOA ns-1338.awsdns-39.org. dcid.sucuri.net. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0