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Query multiple DNS record types for a domain at once
Check MX, SPF, DMARC, DKIM and more for any domain
Test latency to multiple hosts at once — useful for comparing CDNs and DNS providers
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⬇ Download NetworkInfo.exeMost email deliverability problems and network connectivity issues come down to a handful of root causes that are straightforward to diagnose once you know where to look. Whether an email is landing in spam, a domain change hasn't propagated, or you're trying to verify someone's DNS configuration before a migration, these tools give you the raw data you need without having to install anything or open a terminal.
After 25 years of managing IT infrastructure for businesses across the UK, the same diagnostic questions come up repeatedly: is SPF set up correctly? Why is email being rejected? What's the MX record pointing to? Has the DNS change gone through yet? This page puts all of those answers in one place.
SPF (Sender Policy Framework) is a DNS record that lists which mail servers are authorised to send email on behalf of your domain. When a receiving mail server gets an email claiming to be from your domain, it checks your SPF record to verify the sending server is on the approved list. If it isn't, the email fails SPF — and depending on your DMARC policy, it may be rejected or sent to spam. A common mistake is having multiple SPF records for the same domain, or using too many DNS lookups within a single record (the limit is 10). Both cause silent failures that are hard to trace without the right tools.
DKIM (DomainKeys Identified Mail) works differently — it adds a digital signature to outgoing emails using a private key held by your mail server. The corresponding public key is published in your DNS. Receiving servers verify the signature against the public key to confirm the email hasn't been tampered with in transit and genuinely came from an authorised sender. DKIM is especially important for bulk email senders and platforms like Microsoft 365, Google Workspace, and third-party CRM tools. Each sending platform typically needs its own DKIM selector configured in your DNS.
DMARC (Domain-based Message Authentication, Reporting and Conformance) ties SPF and DKIM together by telling receiving mail servers what to do
when an email fails authentication — whether to do nothing (monitor only), quarantine it to spam, or reject it outright. A DMARC policy of p=reject
is the gold standard, but many organisations start with p=none (monitoring mode) before tightening the policy once they're confident all legitimate sending sources are covered.
Without DMARC, anyone can send email appearing to come from your domain — a technique used in phishing and business email compromise attacks.
The Domain Name System (DNS) is essentially the internet's phone book — translating human-readable domain names into IP addresses and other records that computers use to route traffic. When you change a DNS record (updating MX records for a mail migration, adding an SPF record, or pointing a domain to a new server), the change doesn't take effect immediately. It propagates gradually across DNS resolvers around the world, a process governed by the TTL (Time to Live) value of each record. A TTL of 3600 means resolvers cache the old value for up to an hour before checking for updates. During a migration, lowering your TTL to 300 (5 minutes) before making changes gives you much faster propagation and easier rollback if something goes wrong.
Common DNS record types you'll encounter in day-to-day IT work include: A records (domain to IPv4 address), AAAA records (domain to IPv6 address), MX records (mail server routing), CNAME records (domain aliases), TXT records (used for SPF, DKIM, domain verification, and more), and NS records (which nameservers are authoritative for a domain). The DNS checker above queries all of these and returns the live results directly from the authoritative nameservers, so you see exactly what the internet sees for any domain.
SPF passing alone isn't enough. If DKIM fails or isn't configured, and DMARC is set to quarantine or reject, the email may still be treated as suspicious. Check all three — SPF, DKIM, and DMARC — together. Also check whether your sending IP or domain has a poor reputation score with major spam filter providers.
It depends on the TTL of the record being changed. Most records with a TTL of 3600 (1 hour) will propagate globally within 1-4 hours. Some ISPs and resolvers cache aggressively and can take up to 48 hours in rare cases. Lowering your TTL to 300-600 seconds before a planned change significantly speeds this up.
An A record maps a domain or subdomain to an IP address — used for websites and servers. An MX record (Mail Exchanger) specifies which server handles incoming email for the domain. When someone sends an email to you@yourdomain.com, the sending server looks up the MX record to know where to deliver it.
Yes — DNS records are publicly accessible by design. Any domain's MX, SPF, DMARC, DKIM, and A records can be queried by anyone. This is intentional, as email systems around the world need to look up these records to deliver and authenticate email correctly.