April 22, 2026 · 9 min read
What Is DNS Resolution? A Records, AAAA, and DNS over HTTPS (DoH)
How hostnames become IP addresses, why A and AAAA matter, what DNS over HTTPS changes on the wire, and what a normal website can (and cannot) discover about your DNS settings.
When you type a hostname or click a link, your software needs an IP address before it can open a connection. DNS (the Domain Name System) is the distributed directory that answers “what addresses belong to this name?” That answer path — from your stub resolver to recursive resolvers and sometimes authoritative nameservers — is what people mean by DNS resolution.
Records you see most often: A and AAAA
- An A record maps a name to an IPv4 address (dotted decimal).
- An AAAA record maps a name to an IPv6 address (hex groups with colons).
A hostname might have only A, only AAAA, both, or neither (for example if it uses only a CDN alias chain). Our What Is My DNS page asks a public resolver for A and AAAA and shows whatever that resolver returns, with TTL (time to live) hints so you know how long answers may be cached.
Traditional DNS vs DNS over HTTPS (DoH)
Classic DNS often uses UDP (and sometimes TCP) on port 53 between your device and a resolver. On untrusted networks, those queries can be observed or modified by middleboxes unless you add encryption (for example DNS over TLS on another port, or DoH).
DoH sends the same logical questions inside HTTPS to an HTTPS endpoint (for example a well-known public resolver). Benefits include:
- Encryption of the query to that resolver on many network paths.
- Shared fate with web traffic — it looks like ordinary HTTPS to many filters.
Tradeoffs include centralization toward whichever resolver you use (it sees your queries) and the fact that local policy DNS (Pi-hole, split-horizon corporate DNS) may not apply if the browser bypasses the OS stub resolver for DoH.
What this site’s DNS tool does — and does not — claim
The browser cannot read your full OS or router “DNS server” list and show it on a page. So we do not pretend to print “your ISP’s DNS.” Instead, the tool runs A and AAAA lookups against Cloudflare’s public DNS over HTTPS endpoint and labels that clearly. That tells you what that resolver returns — useful for quick checks and for comparing with dig or your system resolver offline.
For authoritative debugging (delegation, NS glue, long CNAME chains), command-line tools and your IT stack still matter; this page is a fast, honest browser-side slice of the problem, not a replacement for a full resolver trace.