Technical guides for every NetTools.tech tool — what it does, how it works, how to read the results and how to troubleshoot — plus articles for system administrators, DevOps engineers and security professionals.
Tool guideEmail Tools
What each DMARC tag does, how the NetTools.tech DMARC generator builds and validates the record locally, and how to roll out a policy from p=none to p=reject without blocking legitimate mail.
Tool guideEmail Tools
What DMARC is, how it builds on SPF and DKIM alignment, how the NetTools.tech DMARC Lookup reads _dmarc records, falls back to parent domains and checks external report authorization.
Tool guideDNS & Domains
What a DNS lookup really asks, how to query A, AAAA, CNAME, MX, NS, TXT, SOA, CAA and SRV records online, and how to read NXDOMAIN, empty answers and TTLs.
Tool guideDNS & Domains
DNS changes are not pushed anywhere: resolvers serve cached answers until the TTL expires. How to compare many public resolvers, read matching and different answers, and plan record changes.
Tool guideEmail Tools
A quick yes/no blocklist overview for a mail server IP or domain: how DNSBL checks work, which default lists the NetTools.tech Email Blacklist Check queries, and how to act on a listing.
Tool guideEmail Tools
Why email DNS changes take time to appear, how the NetTools.tech Email DNS Propagation checker compares one email record across eight public resolvers, and how to read mixed answers.
Tool guideEmail Tools
How email headers record a message's route and authentication, how to get the raw headers from common mail clients, and how the NetTools.tech Email Header Analyzer parses them entirely in your browser.
Tool guideEmail Tools
What the NetTools.tech Email Health Check runs (MX, SPF, DMARC, DKIM with a selector, MTA-STS, TLS-RPT and one SMTP test), how to read the pass/warning/problem table, and what it deliberately leaves out.
Tool guideEmail Tools
What Gmail and Yahoo require from bulk senders, which of those requirements the NetTools.tech compliance check can verify from DNS and one SMTP connection, and which ones need a real message or provider data.
Tool guideWeb & SEO Utilities
What HTTP status codes and response headers tell you, how the NetTools.tech HTTP Status checker requests a URL and follows redirects, and how to troubleshoot what it reports.
Tool guideNetwork Diagnostics
How the NetTools.tech speed test measures throughput and latency from your browser, what Mbps, ping, jitter, request loss and the quality score mean, and how to test fairly.
Tool guideConversion & Calculation Tools
What an IP address is as a number, how the NetTools.tech converter parses dotted, integer, hex, binary and IPv6 input, and what every output form — from in-addr.arpa names to IPv4-mapped IPv6 — means.
Tool guideIP & Network Utilities
What IP geolocation can and cannot tell you, how databases such as DB-IP Lite map address blocks to places, why anycast, VPN and mobile networks confuse them, and how to read the NetTools location map alongside registry and routing data.
Tool guideIP & Network Utilities
How to find the organization behind an IP address with RDAP, BGP origin data and reverse DNS, why the registered owner and the routing network can differ, and how to use the results for abuse reports and firewall decisions.
Tool guideWeb & SEO Utilities
How the NetTools.tech Is It Down check tests a website from our server, how to read its up/down verdict and hop table, and how to troubleshoot a site that fails only for you.
Tool guideWeb & SEO Utilities
llms.txt is a proposed convention, not a standard. This guide explains its Markdown structure, how the NetTools.tech llms.txt Checker parses and validates it, and what publishing one can and cannot achieve.
Tool guideIP & Network Utilities
How MAC addresses are structured, how the IEEE OUI registry maps prefixes to manufacturers, why phones and laptops use randomized addresses, and how to use a vendor lookup when identifying unknown devices on a network.
Tool guideWeb & SEO Utilities
What the important SEO meta tags do, how the NetTools.tech Meta Tag Analyzer reads them from a live page or pasted HTML, and how to interpret its checks and search-result preview.
Tool guideEmail Tools
What MTA-STS is, how the NetTools.tech MTA-STS Lookup checks the _mta-sts TXT record and the HTTPS policy file against your MX hosts, and how to troubleshoot a broken policy.
Tool guideNetwork Diagnostics
What MTR (My Traceroute) measures, how to configure ICMP, UDP and TCP tests, how to read loss and latency per hop, and why loss at one router is usually not a problem.
Tool guideEmail Tools
How RBL and DNSBL queries work, which lists the NetTools.tech MultiRBL Check queries through its own resolver, what listed, not listed, timeout and provider unavailable mean, and what to do when an IP is listed.
Tool guideEmail Tools
What MX records are, how sending servers use them, how to read the NetTools.tech MX lookup (priority, addresses, reverse DNS, null MX) and how to troubleshoot mail routing.
Tool guideNetwork Diagnostics
How the NetTools.tech jitter test measures round-trip variation in browser (HTTP) and server (ICMP) mode, how jitter is calculated, and how to read the stability rating.
Tool guideConversion & Calculation Tools
How bases 2 to 36 work, how the NetTools.tech converter reads prefixes and separators, converts arbitrarily large integers exactly with BigInt, and shows two's-complement patterns for negative numbers.