Reference
Tool Reference
67 checks, grouped by the part of the stack they interrogate. Each page covers what the check actually tells you, when it is worth running, and what changes when you stop running it by hand.
DNS & Domains
DNS is where most outages start and where the fewest people look first. These tools answer what a resolver actually returns, how far a change has spread, and how long you have before something expires.
- DNS Query Tool Run dig against any resolver to see the exact DNS answer, flags and TTL a client receives — not a cached guess from you…
- Domain Name Lookup Look up A, MX, TXT and other records for a domain with nslookup — the fastest way to confirm what a name resolves to ri…
- Quick DNS Lookup The host command gives the shortest useful DNS answer — forward, reverse and mail records in one line each, with no pro…
- DNSSEC Query Tool drill traces a DNSSEC chain of trust from the root down, showing exactly which link fails when validation breaks and re…
- DNS Resolver Query A, AAAA, MX, TXT, CNAME, NS and more against your choice of public resolver, and compare what different resolvers…
- DNS Check Audit a domain's complete DNS configuration in one pass — nameservers, addresses, mail records and the misconfiguration…
- IPv4 Address Lookup Resolve a hostname's A records to see the IPv4 addresses it currently returns, and how many hosts are actually behind t…
- All DNS Records Enumerate every DNS record type a domain publishes in one query, including the text records carrying mail and security …
- DNSSEC Validator Check that a domain's DNSSEC signatures validate from the root down, and catch a broken chain before validating resolve…
- DNSSEC Signature Expiration Report how many days remain on a domain's DNSSEC signatures, so a stalled resigning process is found long before valida…
- Domain Expiration Track the registration expiry date of every domain you own, so a lapsed renewal is caught during the grace period rathe…
- Whois Look up a domain's registration record — registrar, dates, status codes and nameservers — to confirm ownership and spot…
- Reverse IP Resolve an IP address back to its PTR record to confirm reverse DNS matches forward DNS — the check mail servers make a…
- DNS Propagation Check Query dozens of public resolvers worldwide at once to see how far a DNS change has spread, and separate normal propagat…
- DNS Load Tester Benchmark a DNS server's queries-per-second and response latency under sustained load, before production traffic finds …
- DNS Capacity Tester Ramp query load steadily against a DNS server to find the exact rate where latency climbs and answers start being lost …
TLS & Certificates
A certificate problem is a total outage with no warning and no partial failure mode. These tools inspect the chain a client is actually served, not the one you think you deployed.
- Certificate Expiration Check Check how many days remain on the certificate a host is really serving, per hostname, so a failed renewal is caught whi…
- TLS Deep Scan Audit a host's complete TLS posture: chain validity, OCSP stapling, supported protocol versions and the cipher suites o…
- TLS Quick Scan Enumerate the protocol versions and cipher suites a host accepts, quickly — the fast first pass before committing to a …
- TLS Handshake Inspector Open a raw TLS connection and inspect the full handshake — every certificate the server sends, the negotiated parameter…
- Certificate Transparency Search Search public Certificate Transparency logs for every certificate issued for a domain — including the ones you did not …
Email Deliverability
Email fails quietly. Nothing bounces, nothing alerts, and the first symptom is a customer saying they never received it. These tools check the records that decide whether you land in the inbox.
- Email Health Scorecard Grade a domain's whole mail configuration in one pass — authentication records, mail servers, blacklist status and DNS …
- SPF Record Checker Validate a domain's SPF record: syntax, the ten-lookup limit, include chains and the all mechanism that decides what ha…
- DKIM Record Checker Look up a DKIM selector's public key in DNS and confirm it is present, well-formed and strong enough for receiving serv…
- DMARC Record Checker Parse a domain's DMARC record: policy, alignment mode, reporting addresses and subdomain handling — and whether the pol…
- Mail Records Audit Retrieve and validate a domain's complete mail authentication set in one pass — MX, SPF, DMARC and DKIM selectors, with…
- MX Record Lookup Resolve a domain's MX records with their priorities, confirm each host resolves, and catch the misconfigurations that s…
- SMTP Banner Probe Connect to a mail server, capture its greeting and advertised capabilities, and confirm STARTTLS is offered and actuall…
- Mail Blacklist Check Check a domain's mail server addresses against dozens of IP and domain blacklists, and find out you are listed before y…
- MTA-STS Policy Checker Validate a domain's MTA-STS policy: the DNS record, the served policy file, its mode and MX list, and whether the two agree.
- TLS-RPT Checker Verify a domain's TLS-RPT record so sending servers can report failed encrypted delivery attempts to you — the only fee…
- BIMI Record Checker Validate a domain's BIMI record, the SVG logo it points to, and the DMARC enforcement BIMI requires before any mail cli…
Network Path & Reachability
When something is slow or unreachable, the question is which hop is responsible. These tools narrow it from "the internet is broken" to a specific link, host or port.
- Ping Send ICMP echo requests to measure round-trip time and packet loss — the baseline measurement every other network diagn…
- Traceroute Map the network path to a host hop by hop with per-hop latency, and learn which of the results are genuinely a problem …
- Network Path Monitor Combine traceroute's path map with ping's repeated sampling to see sustained per-hop loss and latency — the tool that a…
- Ping Sweep Probe an entire list or range of hosts in parallel to see which are alive, in the time a sequential ping would take for one.
- Port Connection Test Open a raw TCP or UDP connection to a specific port to separate a firewall problem from an application problem — the fa…
- HTTP Availability Sweep Probe a list of hostnames for HTTP and HTTPS availability at once, and discover which of them are serving web traffic y…
- HTTP Quick Check Request a URL and report status code and response time — the simplest possible availability check, and the one worth ru…
- Path MTU Probe Discover the largest packet size that traverses a path intact, and diagnose the connections that establish fine and the…
- HTTP Latency Measurement Break an HTTP request into its phases — DNS, connect, TLS, first byte, transfer — to see which one is actually responsi…
- NTP Time Check Query a time server and measure clock offset, because a drifting clock breaks certificate validation, authentication an…
- SSH Host Key Scanner Retrieve a server's SSH host keys and fingerprints to verify identity, pre-populate known_hosts, and detect a key chang…
HTTP & Web Delivery
A 200 response proves a server answered, not that it answered correctly or quickly. These tools inspect the full exchange — headers, redirects, timing and payload.
- HTTP Request Builder Build an HTTP request with full control over method, headers, authentication and body, and see the complete unmodified …
- HTTP Header Inspector Inspect the response headers a URL returns, including the caching, compression and security headers your CDN or proxy a…
- Page Load Timing Load a URL in a real headless browser and capture every request it makes, with timing — the view that shows what the pa…
- Browser Flow Check Replay a multi-step journey in a real browser — log in, navigate, assert — to catch the failures that return a perfectl…
- CORS Policy Test Test a server's cross-origin headers, including the preflight exchange, to find out why a browser is blocking a request…
- HTTP/2 Probe Confirm whether a host genuinely negotiates HTTP/2, and inspect the stream-level behaviour and settings it advertises d…
- HTTP/2 Load Generator Drive concurrent HTTP/1.1 or HTTP/2 load at an endpoint and measure throughput, latency distribution and the concurrenc…
Security & Exposure
Exposure accumulates: a forgotten port, a stale certificate authority record, a debug endpoint left enabled. These tools enumerate what is reachable from outside your network.
- Port Scanner Scan a host for open TCP and UDP ports and identify the services behind them, to see the attack surface you are present…
- Site Exposure Scan Probe a site for exposed configuration files, version control directories, admin panels and debug endpoints that were n…
- Security Header Grade Grade the security headers a site returns — HSTS, CSP, frame options and the rest — and catch the ones a proxy is silen…
- CAA Record Checker Check a domain's CAA records to control which certificate authorities are permitted to issue for it, and to catch a rec…
- OCSP Revocation Checker Check a certificate's revocation status and whether the server staples the response, since stapling failures add latenc…
- Deep TLS Security Audit Run an exhaustive TLS assessment covering protocol versions, cipher suites, certificate details and the named vulnerabi…
- TLS Implementation Fingerprinter Fingerprint a server's TLS implementation from its handshake behaviour to identify what is actually terminating the con…
- Web Vulnerability Scanner Scan a web server for known vulnerabilities, outdated components, dangerous default files and configuration problems, f…
- Threat Surface Probe Run a community-maintained template library against a target to check for current CVEs, exposed panels, misconfiguratio…
Addressing & Routing
The reference layer underneath everything else — what an address belongs to, which prefix announces it, and whether the subnet maths you did in your head was right.
- Subnet Calculator Work out network address, broadcast, usable host range and mask for any CIDR block, and check whether two subnets overl…
- IP Address Analyzer Analyse any IPv4 or IPv6 address or block in detail — classification, expansions, splits and every representation you n…
- IPv4 / IPv6 Converter Convert between IPv4 and its IPv6 representations — mapped, compatible and translation-embedded — and understand which …
- IP Geolocation Look up the approximate location, network operator and autonomous system behind an IP address — with a realistic view o…
- MAC OUI Lookup Resolve the manufacturer behind a MAC address prefix to identify unknown devices on a network, and understand why rando…
- IP Blacklist Check Check a single IP address against a broad set of blocklists, whether it is one of yours or one you are deciding whether…
- Looking Glass (BGP) Query routing tables from other networks' vantage points to see how the rest of the internet reaches your prefixes — an…
- IRR Route Filter Generator Generate router prefix lists and AS paths from internet routing registry data, so filters stay correct as peers change …