Free DNS, IP & Email Diagnostics Tools
23 professional network and mail server diagnostic tools. Check DNS records, validate SPF/DKIM/DMARC, scan ports, test SSL and monitor blacklists — instantly, no signup required.
🌐 DNS Tools
DNS Checker
Look up A, AAAA, MX, TXT, CNAME, NS, SOA and PTR records for any domain.
DNS Propagation Checker
Check how a DNS record resolves across Google, Cloudflare, OpenDNS and Quad9.
Reverse DNS Lookup
Find the PTR (reverse DNS) hostname configured for an IP address.
WHOIS Lookup
Look up registrar, registration dates, name servers and status for any domain.
✉️ Email Tools
MX Lookup
List a domain's MX records with priority, resolved IPs and SMTP reachability.
SPF Validator
Fetch and validate a domain's SPF record, including the 10-DNS-lookup limit.
SPF Generator
Build a valid SPF TXT record with IPs, includes and provider presets.
DKIM Validator
Check a DKIM selector's public key record, algorithm and key length.
DKIM Generator
Generate a DKIM RSA key pair and the DNS TXT record for your selector.
DMARC Analyzer
Analyze a domain's DMARC policy with warnings and a health score.
DMARC Generator
Create a DMARC TXT record with policy, reporting and alignment settings.
Email Header Analyzer
Paste raw email headers to trace the delivery route and authentication results.
SMTP Diagnostics
Test a mail server's SMTP ports, banner, STARTTLS support and reverse DNS.
SMTP Tester
Interactive SMTP test on port 25, 465 or 587 with TLS, MAIL FROM and RCPT TO checks.
📍 IP Tools
IP Lookup
Get ISP, ASN, location, organization and reverse DNS for any IPv4 or IPv6 address.
Blacklist Checker
Check an IP against major DNS blacklists: Spamhaus, SpamCop, Barracuda, SORBS, UCEPROTECT.
Domain Blacklist Checker
Check a domain on URI blocklists (DBL, SURBL, URIBL) and blacklist status of its MX IPs.