Network Diagnostics (DNS, TCP Ping, WHOIS)

Network diagnostics: IP and ASN resolution, full DNS, propagation, TCP ping and WHOIS (RDAP).

Network
Miscellaneous Utilities
Free

IPv4/IPv6 addresses, CNAME chain, reverse DNS and the network operator (ASN) of each IP.

Ready to diagnose

Enter a target then run Resolution.

About

Network Diagnostics (DNS, TCP Ping, WHOIS)

Diagnose a domain, an IPv4 or an IPv6 address without opening a terminal. Queries run from our servers: DNS-over-HTTPS for real TTLs and DNSSEC status, 5 public resolvers compared to follow a propagation, TCP connections to tell whether a port is open, closed or filtered, and RDAP, the official WHOIS successor, for the registrar, dates and IP owner. Paste a URL or an email address: only the host name is kept. Only test systems you are responsible for or authorized to test.

What it does

Resolution: IPv4/IPv6 addresses, CNAME chain, reverse DNS (PTR), network operator (ASN) of each IP and FCrDNS check
DNS: A, AAAA, CNAME, MX, NS, TXT, SOA, CAA, SRV, DS, DNSKEY and HTTPS with real TTL and DNSSEC status
Propagation: answers from Cloudflare, Google, AdGuard, DNS.SB and AliDNS compared
TCP ping: 4 connections on the chosen port (443, 80, 22, 25, 53, 3389 or custom), latency, jitter and open / closed / filtered verdict
WHOIS via RDAP: registrar, creation, expiry, EPP statuses, name servers, DNSSEC, network and abuse contact of an IP
One-click full diagnostic, raw output, copy, .txt export and shareable link

Frequently asked questions

Is the ping a real ICMP ping?

No. The TCP ping opens 4 successive connections to the chosen port (443 by default) from our servers and measures them. It tells you whether a service listens (open port), whether the host refuses the connection (closed port) or whether a firewall stays silent (filtered port). For an ICMP ping or a traceroute, use ping and tracert/traceroute on your computer.

Why compare several DNS resolvers?

After a DNS change, each resolver keeps the previous answer until its TTL expires. The Propagation tab queries 5 public resolvers at once to check whether the change is visible everywhere. Different answers are also normal for a CDN that answers by location.

Which targets can I enter?

A domain or subdomain (api.example.com), an IPv4 or an IPv6 address. A full URL or an email address is accepted: only the host name is used. Local, private and reserved networks are not tested by the TCP ping.

Where does the WHOIS information come from?

From RDAP, the protocol that replaced text WHOIS: the query is redirected to the domain's official registry (Verisign, AFNIC…) or to the IP's regional registry (RIPE, ARIN…). A few extensions, such as .de, do not offer RDAP yet.