Free tool
DNS checker.
Enter a domain to look up its A, MX, TXT, NS, and CNAME records.
What to check
A = IP address. MX = mail server. TXT = SPF, DKIM, DMARC. NS = nameservers. CNAME = aliases.
Why it matters
Broken MX records stop email delivery. Missing TXT records cause spam placement. Wrong NS means DNS is not controlled.
Common issue
CNAME conflicts: you cannot have a CNAME and other records on the same name.