Tool guideDNS & Domains
Nslookup – Complete Guide to DNS Record Lookups
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.
DNS & Domains guides
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 guideDNS & Domains
DNS Propagation Checker – Complete Guide to DNS Caching, TTL and Record Changes
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 guideDNS & Domains
DNS Open Resolver Checker – Complete Guide to Open Recursive DNS and Amplification
How to find out whether your router, firewall or DNS server answers recursive queries for anyone on the internet, what the RA and AA flags mean, and how to close an open resolver.
Tool guideDNS & Domains
Reverse DNS Lookup – Complete Guide to PTR Records
What PTR records are, how an IPv4 or IPv6 address becomes an in-addr.arpa or ip6.arpa name, who controls reverse DNS, and why it matters for mail servers and logs.
Tool guideDNS & Domains
SSL Checker – Complete Guide to TLS Certificates, Chains and Expiry
What an SSL/TLS certificate check verifies, how trust chains and subject alternative names work, how to read expiry, issuer and protocol details, and how to fix common certificate errors.
Tool guideDNS & Domains
Whois Lookup – Complete Guide to Domain and IP Registration Data (RDAP and WHOIS)
What WHOIS and its successor RDAP return for domains and IP networks, how the authoritative registry is found, how to read status codes and dates, and what the data cannot tell you.
Category guideDNS & Domains
DNS & Domain Tools – Complete Guide to DNS Lookups, Propagation, WHOIS and Certificates
An overview of the NetTools.tech DNS and domain tools: what each one checks, which to reach for when a domain does not resolve, a change is not visible or a certificate fails, and how to combine them.