Free DNS and network tools

Free DNS and network tools that show what the internet sees

Check DNS propagation, run a WHOIS or IP lookup, test a port and verify SPF, DKIM and DMARC. No sign-up, no install, results in seconds.

What is my IP address · Subnet calculator · MAC address lookup

  • No sign-up
  • 10 public resolvers
  • DNS over HTTPS
  • IPv4 and IPv6
  • 23free network tools
  • 10public DNS resolvers queried
  • 10DNS blocklists checked
  • 0accounts or sign-ups needed
All tools

23 free network tools in four groups

Pick the group that matches your problem. Every tool answers one question and links to the next check.

DNS tools

Check records, find out when a change has gone live, and see who runs the public resolvers.

Domain tools

Find the registrar and expiry date, or see whether a name is free to register.

  • WHOISSee a domain's registrar, expiry date and nameservers.
  • Domain ExpirationSee when a domain expires and how many days are left.
  • Domain CheckCheck whether a domain name is available across several extensions.

IP and network tools

Locate an address, test a port, plan a subnet or look up a device maker.

  • IP LookupFind the location, ISP and network (ASN) behind any IP or hostname.
  • IP WHOISSee which organization owns an IP address range.
  • My IPSee your public IP address, location and ISP instantly.
  • IPv6 TestCheck whether your connection supports IPv6.
  • Port CheckerTest whether a TCP port is open on a public host.
  • Subnet CalcWork out the network, host range and mask for any IPv4 subnet.
  • IPv6 Subnet CalcWork out the range, size and /64 count of any IPv6 network, and split it.
  • Blacklist CheckerCheck an IP or domain against 10 email blocklists.
  • MAC LookupFind the manufacturer of a device from its MAC address.

Email authentication tools

Verify the records that decide whether your mail reaches the inbox.

Common questions

What do you need to find out?

DNS propagation

Did my DNS change go live?

Compare answers from 10 resolvers and see who still serves the old record. WHOIS

Who owns this domain and when does it expire?

Registrar, creation and expiry dates, status codes and nameservers. My IP

What is my IP address?

See your public IPv4 and IPv6 address, location and provider. Port checker

Is my port forwarding working?

Test whether a TCP port answers from the internet. Blacklist

Is my mail server on a blacklist?

Check an IP against 10 DNS blocklists in one pass. Email authentication

Why does my email go to spam?

Validate SPF, DKIM and DMARC and read plain-language fixes.
How it works

Live queries, not cached reports

Each check runs when you press the button, against the same public services your visitors and mail servers use.

  1. 01

    Enter a name or address

    A domain, an IPv4 or IPv6 address, or a MAC address.

  2. 02

    We ask public servers

    DNS resolvers over DNS over HTTPS, registry RDAP services and DNS blocklists.

  3. 03

    Read a plain verdict

    Consistent, inconsistent or no answer, with the raw records beneath.

Learn the basics

DNS, IP addresses and mail authentication in plain words

What is DNS propagation?

When you change a DNS record, resolvers around the world keep their cached copy until the record's TTL runs out. For a while some show the old value and some the new one. Use the DNS propagation checker to see which is which.

What does an IP lookup show?

An IP address lookup returns the approximate location, the provider, the ASN and the reverse DNS name. Location is an estimate. The ASN, which names the network operator, is the most reliable part.

Why do emails land in spam?

Receiving servers check that SPF, DKIM and DMARC records match the sender. A missing or broken record is the usual cause. Test each one with the SPF checker, DKIM checker and DMARC checker.

Changed a DNS record? Check it now.

See which of 10 resolvers already serve the new value.

Check DNS propagation

Frequently asked questions

Is NetProbe free to use?

Yes. Every tool is free, with no account and no sign-up. Heavier tools such as the port checker have a rate limit to stop abuse.

Which DNS record types can I check?

A and AAAA (IPv4 and IPv6 addresses), MX (mail servers), NS (nameservers), TXT (SPF, verification and other text records), CNAME (aliases) and SOA (zone authority information).

How accurate is IP geolocation?

Usually right at country level and often at city level, but it is an estimate. It often points to the provider's regional hub, not to a street address. The ASN, which names the network operator, is the most reliable part.

Why do results differ from what I see on my own network?

Our queries come from our servers, not yours. Caches, geo-based DNS and your own resolver can each return a different answer, so a difference is not always a fault.

Do you store the domains and addresses I look up?

We do not ask for personal details and we do not sell data. The privacy policy lists which third-party services receive a lookup for each tool.