If you are running Home Assistant with external access, a custom domain, or email notifications, DNS matters more than most guides let on. A misconfigured SPF record means your HA alerts go to spam. A failed DKIM check means your notification emails look suspicious to receiving servers. Slow DNS propagation after switching providers can break access to your instance for hours before you realise why.
These tools cover the checks I run whenever I change anything DNS-related. They work against your live DNS records, so what you see here is what the outside world sees.
DNS Propagation Checker
Use this after changing a DNS record and you want to know if the update has spread globally. DNS changes can take anywhere from a few minutes to 48 hours depending on your TTL settings and your registrar. This tool queries multiple resolvers around the world so you can see which regions have picked up the change and which are still serving the old record.
DNS Propagation Checker
Check how a DNS record is resolving across 8 global nameservers
WHOIS Lookup
Use this to check domain ownership and registration details for any domain. Useful for verifying expiry dates on domains you manage, checking who owns a domain before you set up a subdomain pointing to their service, or confirming your own registrar details are accurate.
WHOIS Lookup
Look up domain registration details, expiry dates, and nameservers
IP Lookup
Use this to find the geographic location and ISP associated with any public IP address. Useful for verifying what IP your external services are resolving to, checking whether a dynamic IP has changed, or investigating an unfamiliar IP showing up in your HA logs.
IP Lookup
Look up geolocation, ISP, and network details for any IP address
SPF Checker
Use this to verify your domain’s SPF record is correctly configured. SPF tells receiving mail servers which IPs are authorised to send email on behalf of your domain. If your Home Assistant notifications are landing in spam, a missing or broken SPF record is one of the first things to check.
SPF Record Checker
Look up and parse your SPF record in plain English
DMARC Checker
Use this to verify your DMARC policy is published and readable. DMARC builds on SPF and DKIM to tell receiving servers what to do with messages that fail authentication. A missing DMARC record means you have no policy in place, which can affect email deliverability and leaves your domain more vulnerable to spoofing.
DMARC Record Checker
Look up and parse your DMARC policy in plain English
DKIM Checker
Use this to verify your DKIM signature record for a given domain and selector. DKIM adds a cryptographic signature to outgoing mail so receiving servers can confirm the message was not tampered with in transit. If you are using a custom domain for Home Assistant email alerts or any self-hosted mail service, DKIM should be configured and verifiable.
DKIM Record Checker
Auto-discover DKIM selectors or enter one manually to verify your DKIM setup
Note: These tools query live DNS records. Results reflect what public resolvers currently see, which may differ briefly from your registrar’s control panel during propagation. If you are on shared hosting, some lookups may be limited by what your host exposes publicly.
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