Networking & DNS Tools
DNS lookups, DNS propagation comparison, port reference and IPv6 conversion - with the record types explained.
DNS is the area where "it works for me" is most often literally true: your resolver has the new record and the resolver your customer uses still has the old one. The lookup tool queries specific record types (A, AAAA, CNAME, MX, TXT, NS) over DNS-over-HTTPS and explains what each record is for, and the propagation tool compares the answer across several public resolvers so you can see whether the difference is real or local.
Use the lookup when a site will not resolve and you need to know whether the record exists at all; use the propagation comparison when you have just changed a record and want to know whether it is worth waiting. The port reference answers the other half of networking questions - what is this port for, and should it be open - and it is the tool to reach for before you write a firewall rule rather than after.
Common mistakes worth knowing: a CNAME at the apex of a zone is not allowed, TTL changes do not retroactively speed up caches that already hold the old record, and a missing trailing dot turns a fully-qualified name into a relative one. Each lookup names the record type it returned and what that means, instead of printing a wall of JSON.
3 tools in this category
- Port Number Lookup — Look up TCP/UDP ports: service, typical use & security notes.
- DNS Lookup & Record Explainer — Look up A, AAAA, CNAME, MX, TXT & NS records via DNS-over-HTTPS with plain-English
- DNS Propagation Comparison — Compare DNS answers across Google, Cloudflare and other resolvers.
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