DNS Tools

Query any DNS record type, test a domain's email security — SPF, DMARC and DKIM — and check mail-server spam blacklists.

DNS lookup

Email security check (SPF / DMARC / DKIM)

Checks whether a domain is protected against email spoofing. DKIM selector is optional — common ones: selector1 / selector2 (Microsoft 365), google (Google Workspace).

Mail-server blacklist check (DNSBL)

Checks whether a mail server's IPv4 address is listed on the major spam blacklists — the first thing to rule out when a customer says "our emails are bouncing".

Record type cheat-sheet

A	Hostname → IPv4 address
AAAA	Hostname → IPv6 address
MX	Mail servers (lower priority wins)
NS	Authoritative name servers
TXT	Free text — SPF, verification keys
CNAME	Alias to another hostname
SOA	Zone authority + serial
CAA	Which CAs may issue certificates
SRV	Service location (port + host)
PTR	IP → hostname (reverse DNS)

Why SPF + DKIM + DMARC?

SPF lists the servers allowed to send mail for your domain. DKIM cryptographically signs each message. DMARC tells receivers what to do when both fail — and sends you reports. All three together stop most domain spoofing; any one alone leaves gaps. Aim for SPF ending in -all, a valid DKIM key, and DMARC at p=quarantine or p=reject.