My IP Check
Your public IP address and network location, detected automatically.
Loads automatically when you open NetChecks — no input needed. Use the Refresh button to re-check after switching networks or reconnecting your VPN.
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All-in-One Scan
Runs every relevant check against one IP or hostname in a single pass: DNS, whois, ping, traceroute, a well-known-ports scan (1-1024), HTTP headers and the SSL certificate.
Enter a domain or IP address and run it to check DNS, whois, ping, traceroute, common ports, HTTP headers, and the SSL certificate all at once.
Most checks run in parallel - typically finishes in about 30 seconds, longer if the target is slow or unreachable.
The port scan step only runs once the consent checkbox above is checked - every other check runs regardless.
Ping
Send ICMP echo requests to a host to check reachability and latency.
Enter a hostname or IP address and press Ping to send ICMP echo requests and measure round-trip latency.
Traceroute
Trace the network path (hop by hop) to a destination host.
Enter a hostname or IP address and run it to see every network hop between this server and the destination, with latency per hop.
DNS Lookup (Nslookup)
Query DNS records: A, AAAA, MX, TXT, NS, CNAME, SOA, PTR, SRV, CAA.
Enter a domain, choose a record type (A, AAAA, MX, TXT, NS, CNAME, SOA, PTR, SRV, or CAA), then look it up.
Learn more about DNS Lookup (Nslookup)
What it is
DNS Lookup queries the Domain Name System for a specific record type tied to a domain: A or AAAA for the IP address (v4 or v6), MX for mail servers, TXT for email verification and security records (SPF, DKIM, DMARC), NS for the authoritative name servers, CNAME for aliases, SOA for zone metadata, PTR for reverse resolution, or SRV for service discovery. DNS is often described as the phone book of the internet, but in practice it carries far more operational information than a simple name-to-IP mapping.
How it works
Resolution follows a well-defined hierarchical chain: the resolver first queries the root servers (which know where each extension's servers are), then the servers for the relevant TLD (.com, .fr, .org...), and finally the servers authoritative for the exact domain, until it gets the final answer. Every record carries a TTL (caching duration, in seconds) that determines how long an old value can keep showing up at a given resolver after a change has been made on the zone side - it is this distributed caching mechanism, present at every stage of the chain, that explains why a DNS change never propagates instantly everywhere in the world.
Reading the results
An A record that does not match the expected IP, or is missing altogether, points either to propagation still in progress (worth comparing against the announced TTL) or to a genuine misconfiguration on the zone side that will persist until fixed at the source. MX records that are missing, or present but wrongly ordered by priority, directly explain emails that fail to be delivered or that take an unwanted fallback route. A malformed, incomplete, or simply missing SPF TXT record is one of the most common causes of outbound emails being marked as spam or outright rejected by major mail providers, which apply increasingly strict checks on this front.
Common mistakes
A frequent point of confusion is querying only your own local DNS resolver (often the one from your box or ISP) and concluding the change "hasn't taken effect yet" everywhere, when in fact that specific resolver is simply still holding the old value in cache until its TTL expires - other resolvers around the world may already be seeing the new value. Another classic trap: forgetting that a CNAME record cannot coexist with any other record type on the exact same name (this is a constraint of the DNS protocol itself), which often silently breaks a configuration when a TXT record is added on a name already covered by a CNAME.
When to use it
Checking DNS propagation after a hosting migration or a name server change, by tracking how the returned values evolve over time. Diagnosing an email deliverability problem by methodically checking MX, SPF, and DKIM records one after another. Confirming that a subdomain delegation or a CNAME record correctly points to the expected resource before declaring a rollout finished. Validating a complete DNS setup before putting a new domain or service into production, ahead of any communication to the client.
Whois
Look up registration information for a domain or IP address.
Enter a domain or IP address to look up its registration details — registrar, owner organization, and important dates.
Blacklist Check
Check whether an IP address or domain is listed on public spam/abuse blocklists (DNSBL).
Enter an IPv4 address or domain and run it to check 7 public DNSBL/RBL blocklists at once - each shows as listed, not listed, or check failed.
TCP Port Scan
Check whether TCP ports are open on a host or IP: common ports, a custom list, or the full 1-65535 range.
Enter a host or IP, pick common ports, a custom list, or the full range, then scan to see which TCP ports respond.
A full range scan can take up to ~100 seconds. Large scans (more than 100 ports, including custom ranges/lists) are limited to 1 per minute per visitor.
Open ports (0)
HTTP Header Inspector
Fetch the HTTP response status and headers for a URL.
Enter a URL to fetch its HTTP response status code and every response header the server sends back.
SSL / TLS Certificate Checker
Inspect a host's TLS certificate: issuer, validity dates, and days remaining.
Enter a hostname to inspect its TLS certificate — issuer, validity dates, and days remaining before it expires.
Geo-IP Lookup
Look up the geographic location and network info for an IP address. Leave empty to look up your own public IP.
Enter any IP address, or leave it empty to look up your own, to see its approximate location and network/ISP info.
Subnet / CIDR Calculator
Computed entirely in your browser — no data sent to the server.
Enter an IP address and CIDR prefix (e.g. 192.168.1.0/24) to instantly compute the network range, broadcast address, and usable host count.
Speed Test
Basic download/upload throughput test against this server (accuracy depends on the server's own uplink).
Press Start to measure download and upload throughput against this server. Accuracy depends on this server's own connection.
Country Code Dictionary
ISO 3166-1 alpha-2 country codes — searched entirely in your browser.
Search or browse the list of ISO 3166-1 alpha-2 country codes, looked up entirely in your browser.
| Country | ISO Code |
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Phone Dialing Code Dictionary
International calling codes by country — searched entirely in your browser.
Search or browse international calling codes by country, looked up entirely in your browser.
| Country | Dial Code |
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World Clock
Pick a time zone to see the current time — drag the globe to spin it.
Pick a time zone from the list, or drag the globe, to see the current time there.
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Drag to rotate the globe.
French Mobile Network Status
Mobile antenna sites down or under maintenance in France, by operator (Orange, Free, SFR, Bouygues Telecom), from ARCEP's public data. Snapshot updated once a day by ARCEP - not a minute-by-minute feed.
Browse mobile antenna and fibre outage data by French operator — no input needed, updated automatically from ARCEP's public data.
Most affected departments
Number of sites currently down or under maintenance, by department. Click an operator above to filter.
Data: Arcep — Sites indisponibles · Official network status map
Fixed Network (Fibre)
Fibre (FTTH) network quality by operator: reported-outage rate and connection-failure rate, from ARCEP's public data. Monthly indicators, 6-month rolling average - not a live feed like the mobile section.
By operator (parent group)
Averages over the last 6 available months, per infrastructure-operator parent group.