Look up any domain's DNS records straight from public resolvers. Compare Cloudflare, Google and AliDNS to see whether a change has spread, or check that your email records (SPF, DKIM, DMARC) are in place.
A and AAAA point a name to an IPv4 or IPv6 address. CNAME makes one name an alias of another. MX lists the servers that receive email. NS lists the servers that hold the domain's DNS. TXT holds text such as SPF, DKIM and verification codes. SOA is the zone's admin record, and CAA says which authorities may issue SSL certificates.
Choose "Compare all three (propagation check)". If the three resolvers show different answers, the change is still spreading - resolvers keep old answers until their TTL (time to live) runs out, which can take minutes or hours.
Choose "Email setup check". It looks for MX records, one SPF record, a DMARC policy and DKIM keys on the common selector names. If something is missing, mail from your domain is more likely to land in spam.
Yes. Enter an IP address and the tool does a reverse lookup (PTR record) to find the host name it belongs to, if one is set.