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.
Your browser
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.
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.
Learn more about Blacklist Check
What it is
Blacklist Check tests an IP address or a domain against several public anti-spam blocklists (DNSBL, DNS-based Blackhole List, also known as RBLs) used daily by the vast majority of mail servers worldwide to automatically filter unwanted mail before it ever reaches the recipient's inbox.
How it works
Each blocklist technically works like an ordinary DNS zone, queryable by anyone: the IP address being checked is reversed octet by octet and then prefixed to the blocklist's own domain name, and a positive DNS response to that query means the IP is indeed listed there. Seven widely recognized public blocklists, commonly consulted by mail servers, are checked here in parallel, to give a representative overall picture of the address's reputation rather than a result that depends on a single source.
Reading the results
Being listed on a single minor or rarely used blocklist generally has very limited real impact on actual deliverability. Being listed on a major, widely deployed blocklist - the best-known and most impactful example being Spamhaus - will block most mail to major consumer mail providers, and requires a quick, well-documented delisting request directly with the operator of that blocklist, who typically explains the exact reason for the listing in their response.
Common mistakes
A common mistake is assuming a listing must be due to deliberate spam sent from that address, when a server can end up listed for plenty of other reasons: a recycled IP that inherited a bad history left behind by a previous tenant at the same host, a compromised server sending spam without its administrator's knowledge, or even a simple shared IP situation where a third party's traffic reflects onto the shared reputation. Another trap: getting delisted does not by itself guarantee good deliverability if the root cause (missing or incorrect SPF/DKIM/DMARC configuration, abnormal sending volume) has not also been addressed.
When to use it
Methodically diagnosing why emails sent from a client's server have suddenly stopped arriving. Proactively checking an IP address's reputation before putting it into production for a new mail server, particularly if it has previously been used elsewhere. Checking that an IP newly reassigned by a host doesn't inherit a bad history left behind by the previous tenant, before using it for anything deliverability-sensitive.
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 |
|---|
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 |
|---|
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.
—
—
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.