DNS & Networking Tools

Almost every problem with a website or a mailbox eventually comes back to DNS: a record that points to the old server, a TTL that keeps a stale answer cached, or a missing TXT entry that sends mail to spam. This category brings together the free lookups that show what the internet actually sees for a domain, in real time, with every record explained. Queries go straight from your browser to public DNS-over-HTTPS resolvers, and nothing you look up is stored.

DNS lookup

The DNS lookup queries A, AAAA, CNAME, MX, NS, TXT, SRV and PTR records for any domain and shows every value with its TTL. Switch between Cloudflare, Google and Quad9 to compare resolvers, run a reverse lookup on an IP address, and copy or export the answers as JSON. Use it after changing a record to confirm the new value is live, or before a migration to capture exactly what is configured today.

SPF, DKIM & DMARC checker

Email authentication lives in DNS too. The SPF, DKIM and DMARC checker reads all three records at once, counts the DNS lookups your SPF record triggers against the limit of ten, finds DKIM keys at common selectors or the one you name, and explains the DMARC policy and where its reports go. Each result comes with a plain verdict and the change that fixes it, which makes it the fastest way to find out why messages land in spam.

When to use these lookups

Reach for them when a website shows the wrong version after a move, when a new subdomain will not resolve, when a certificate request fails domain validation, or when newsletters and invoices stop arriving. They are just as useful for planned work: checking records before you switch hosting, lowering TTLs ahead of a change, and confirming that a mail provider has been set up correctly before you announce it.

Who relies on them

System administrators use them to confirm changes across resolvers, developers use them while wiring up a new environment, and marketers use them when a new email platform asks for SPF and DKIM records. Because the answers come from public resolvers, you see the same thing your visitors and their mail servers see, not a cached view from your own network.

Common DNS mistakes

The same few errors cause most outages: a CNAME placed on the root domain, two SPF records instead of one, a TTL left at a day before a planned move, an MX record that points to an IP address instead of a hostname, or a stray trailing dot missing in a zone file. Checking the live answer after every change, from more than one resolver, catches nearly all of them before your visitors or your email do.

Quick DNS checklist

Before any change, note the current records and lower the TTL a day ahead. After the change, look the record up on two or three resolvers, confirm MX and TXT entries still resolve, and re-check SPF, DKIM and DMARC if mail is involved. Raise the TTL again once everything agrees.

Learn as you check

Every result links to an in-depth guide on record types, propagation and email authentication, so you can understand why a record matters, how long a change will take to spread and which setting to adjust next.

Tip: when you plan to change a record, lower its TTL a day in advance. The change then reaches every resolver within minutes instead of hours, and you can raise the TTL again once everything checks out. Keep a copy of the result so you can compare it after the next change.