1. whois
2. history
$ dig -t txt udemy.com @sri.ns.cloudflare.com udemy.com. 120 IN TXT "v=spf1 include:_spf.google.com include:mktomail.com include:spf.mtasv.net include:mail.zendesk.com include:_spf.salesforce.com -all" ;; Query time: 4 msec ;; SERVER: 172.64.33.234#53(sri.ns.cloudflare.com) (TCP) ;; WHEN: Sun Jul 09 06:28:42 JST 2023 ;; MSG SIZE rcvd: 2513