$ grep -Eo ',"[^"]+"$|,[^",]+$' ~/Downloads/bad-ns-with-fp.csv | fgrep -ve domaincontrol.com -e namecheaphosting.com | sort | uniq -c | sort -rn
17 ,"dns1.registrar-servers.com.,dns2.registrar-servers.com."
16 ,"dns2.registrar-servers.com.,dns1.registrar-servers.com."
6 ,"ns1.vultr.com.,ns2.vultr.com."
5 ,"ns2.vultr.com.,ns1.vultr.com."
2 ,"ns259.mihanwebhost.com.,ns260.mihanwebhost.com."
1 ,ns
1 ,liz.ns.cloudflare.com.
1 ,"ns6.hawkhost.com.,ns5.hawkhost.com."
1 ,"ns5.hawkhost.com.,ns6.hawkhost.com."