DNS Lookup Online
Nslookup / dig online — A, AAAA, MX, TXT, CNAME, NS, CAA, SRV, SOA, PTR
DNS Lookup Online resolves DNS records for any domain — query A (IPv4), AAAA (IPv6), MX (mail), TXT (SPF/DKIM/verification), CNAME (aliases), NS (name servers), CAA (cert authority), SRV (service discovery), SOA and PTR (reverse DNS, enter an IP). A free online alternative to nslookup and dig.
The Port.Tools works well on both desktop and mobile browser.