Live
DNS Lookup
Query A, AAAA, MX, TXT, NS, CNAME, SOA, or CAA records for any domain against a live resolver.
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Free Network & DNS Tools — 21 Browser Utilities for Domain, Email, and Infrastructure Checks
AT USE has twenty-one network and DNS tools that run directly in the browser. No account, no install, no rate limits. They cover DNS record queries, email security validation (SPF, DMARC, DKIM, BIMI), IP diagnostics, and uptime checks — the tasks that pull developers, sysadmins, and domain owners to a separate tab when they’d rather stay in their terminal.
21 live
Network & DNS Tools
DNS Record Lookups
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MX Lookup
List the mail exchange servers configured for a domain, including priority order. Useful for diagnosing email routing failures.
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NS Lookup
Retrieve the authoritative nameservers for a domain or subdomain.
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TXT Lookup
Inspect TXT records: SPF policies, domain verification tokens (Google, Microsoft, Zoho), and DKIM selector references.
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CNAME Lookup
Resolve canonical hostname aliases for domains and subdomains.
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SOA Lookup
Read SOA parameters: serial number, primary nameserver, responsible email, and refresh/retry/TTL intervals.
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CAA Lookup
Check which certificate authorities are authorized to issue SSL certificates for a domain.
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Reverse DNS Lookup
Resolve PTR records: convert an IPv4 address back to a hostname. Standard for mail server reputation checks.
Open toolDomain Research
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WHOIS Lookup
Retrieve registrar, registrant contact, creation date, expiry date, and nameserver assignments for any registered domain.
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DNS Propagation Checker
Verify that a DNS change has reached resolvers across multiple geographic regions. Use this after a nameserver migration or zone update.
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DNS Blacklist Check
Test whether an IP address or domain appears on any major DNSBL or SURBL provider. Runs against the principal blocklists in one check.
Open toolEmail Security — SPF, DMARC, DKIM, BIMI
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SPF Record Checker
Parse and validate an SPF TXT record. Shows include chains, authorized IP ranges, and any syntax errors that cause authentication failures.
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DMARC Record Checker
Read the DMARC policy: enforcement level (reject/quarantine/none), percentage, reporting addresses, and subdomain policy. Flags misconfigurations.
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DKIM Lookup
Retrieve the DKIM public key for a given selector and domain. Verifies the signing key exists in DNS and is formatted correctly.
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BIMI Record Checker
Verify your BIMI TXT record at default._bimi.{domain}. Shows the logo URI and authority evidence URL that Gmail and Yahoo Mail use to display your brand logo.
IP and Network
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IP Address Lookup
Geolocate any IP address: country, region, city, ASN, and ISP. Also shows your own current public IP.
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Subnet Calculator
Calculate network address, broadcast address, usable host range, and available IPs from a CIDR block or IP + subnet mask.
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Port Checker
Test whether a specific TCP port is open and reachable on any host from outside your network.
Open toolHTTPS and SSL
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SSL Certificate Checker
Inspect the TLS certificate for any domain: issuer, expiry date, Subject Alternative Names, and chain validity. Flags expired or self-signed certificates.
Open toolUptime and Website Status
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Online Status Checker
Enter any URL to check whether a website is online or down. Returns the HTTP status code, response time, and a short check history to distinguish an ongoing outage from a one-off timeout.
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OG Tag Previewer
Fetch any public URL and inspect its Open Graph and Twitter Card meta tags. Shows exactly how a page will render as a social share on Facebook, LinkedIn, and X before you post.
Open toolTwenty-one tools for the full network workflow
Built for developers, sysadmins, and domain owners who need live DNS data without leaving the browser.
Each tool queries live DNS resolvers or public data sources and returns results in seconds. DNS Lookup covers all eight standard record types in one query. MX Lookup and Reverse DNS Lookup cover the two most common email deliverability checks. SPF Record Checker, DMARC Record Checker, DKIM Lookup, and BIMI Record Checker cover the complete email authentication and branding stack. WHOIS Lookup surfaces registrar and expiry data. DNS Propagation Checker shows geographic resolver status after a zone change. SSL Certificate Checker flags expired or misconfigured TLS chains. Online Status Checker confirms HTTP reachability with a response time reading.
A standard domain health audit: WHOIS Lookup to confirm the domain is registered and not expiring → DNS Lookup to verify A and MX records → SPF Record Checker, DMARC Record Checker, DKIM Lookup, BIMI Record Checker in sequence for the full email authentication and branding picture → SSL Certificate Checker to confirm TLS is valid → Online Status Checker to confirm HTTP 200. Under five minutes, no account, no rate limits.
All twenty-one tools share the same interface layout and run queries against live resolvers or public APIs. Nothing is stored after you leave the page.
Debugging an email deliverability problem?
Start with DNS Lookup to verify your MX and TXT records, then check SPF, DMARC, and DKIM in sequence.
DNS Lookup →Frequently asked questions
What is a DNS lookup and when do I need one?
A DNS lookup queries the Domain Name System to retrieve records associated with a domain — A records (IPv4 addresses), MX records (mail servers), TXT records (SPF, DKIM, verification tokens), CNAME aliases, and others. You need one whenever you are configuring a domain, migrating hosting, debugging email delivery, or verifying that a change has propagated correctly.
How do I check if my email domain is properly configured with SPF, DMARC, DKIM, and BIMI?
Use four tools in sequence: SPF Record Checker validates your SPF policy and flags include-chain errors; DMARC Record Checker reads your enforcement level and reporting configuration; DKIM Lookup verifies the public signing key exists in DNS for each selector your mail provider uses. Once all three pass, use BIMI Record Checker to confirm your brand logo TXT record is published at default._bimi.{domain} for display in Gmail and Yahoo Mail.
How long does DNS propagation take after I change a record?
Propagation time depends on the record’s TTL (Time to Live). Most registrars set a default TTL of 3,600 seconds (1 hour) to 86,400 seconds (24 hours). If you lower the TTL to 300 seconds before making a change, resolvers that have already cached the old record will refresh within 5 minutes. Use the DNS Propagation Checker to see which geographic regions have picked up the new value.
What does a reverse DNS lookup show?
A reverse DNS lookup queries the PTR record for an IP address, which maps the IP back to a hostname. Mail servers use PTR records as part of spam filtering — if your server’s IP does not have a PTR record pointing to your sending domain, some recipients will reject or junk your mail. ISPs and hosting providers manage PTR records; you typically request one through your host’s control panel.
How can I tell if my IP address or domain is on a blacklist?
Use the DNS Blacklist Check tool. It queries your IP or domain against the major DNSBL (DNS-based Blackhole List) and SURBL providers in a single check. If your IP appears on any list, you will see which list flagged it. Most blacklists provide a removal form; delist requests are typically processed within 24–48 hours if the underlying spam issue has been resolved.
What is the difference between MX, TXT, and CNAME records?
MX (Mail Exchange) records specify which servers receive email for a domain, with a priority order. TXT records store arbitrary text data — commonly SPF email policies, domain ownership verification strings from Google or Microsoft, and DKIM public key references. CNAME (Canonical Name) records create hostname aliases that point one subdomain to another hostname instead of directly to an IP. Each serves a distinct purpose and cannot substitute for the others.