# How DNS Resolution Works

> Follow a DNS lookup through browser cache, recursive resolver, root, TLD, and authoritative nameserver.

Canonical: https://sentryxmonitor.com/learn/networking/dns-resolution/
Last updated: 2026-08-08

Networking and protocol operations

DNS resolution translates a domain name into records by checking caches and, when needed, following referrals from the DNS root to the top-level domain and the authoritative nameserver.

Reviewed 2026-08-08 Read-only educational guidance

## Key points

- Recursive resolvers perform work for clients.

- Authoritative servers publish zone data.

- Caching duration is controlled partly by TTL values.

## How does it work?

A stub resolver asks a recursive resolver. If the answer is not cached, the resolver queries root, TLD, and authoritative servers, then returns and caches the record.

## What can go wrong?

Delegation errors, unavailable authoritative servers, incorrect records, stale caches, DNSSEC failures, and network loss can prevent users from reaching otherwise healthy applications.

## How can teams detect the problem?

Query multiple resolvers and authoritative servers, compare answers, inspect delegation, TTL, response codes, DNSSEC status, and latency.

## How can teams fix or reduce the problem?

Use redundant authoritative DNS, test changes before rollout, monitor records and delegation, and choose TTL values that fit change requirements.

## What does a technical example look like?

```
Browser -> recursive resolver -> root -> .com TLD -> example.com authoritative server -> A/AAAA answer
```

The example uses reserved documentation domains and addresses. Apply the same reasoning to systems you own or are authorized to assess.

## Authoritative technical references

- [RFC 1034: Domain Names - Concepts and Facilities](https://www.rfc-editor.org/rfc/rfc1034.html)

- [RFC 1035: Domain Names - Implementation and Specification](https://www.rfc-editor.org/rfc/rfc1035.html)

## How does continuous monitoring help?

A point-in-time check explains the observed state now. [Continuous monitoring](https://sentryxmonitor.com/services/uptime-monitoring/) establishes an expected baseline, repeats the relevant check, and records meaningful state changes so an owner can investigate before a small configuration drift becomes a prolonged security or availability problem. See [Networking](https://sentryxmonitor.com/learn/networking/) for the surrounding technical context.

## Where does Sentryx Monitor fit?

Sentryx Monitor provides [read-only outside-in discovery](https://sentryxmonitor.com/services/external-attack-surface-monitoring/) and monitoring for public hosts, DNS, HTTPS, TLS certificates, baseline security headers, email-security records, and selected network services. It supports evidence and operational follow-up, but it does not replace authorized penetration testing, authenticated vulnerability assessment, or owner validation.

## Continue learning

- [Internet Networking for Security and Monitoring](https://sentryxmonitor.com/learn/networking/) - The parent networking guide.

- [What Is TCP Port Monitoring?](https://sentryxmonitor.com/learn/networking/tcp-port-monitoring/) - Learn how TCP port monitoring checks service reachability and where it differs from application monitoring.

- [Common Internet-Facing Ports Explained](https://sentryxmonitor.com/learn/networking/internet-facing-ports/) - Understand common public TCP and UDP ports and when exposure deserves review.

- [What Does Port 443 Do?](https://sentryxmonitor.com/learn/networking/port-443/) - Understand how port 443 carries HTTPS traffic and how DNS, TCP, TLS, and HTTP participate.

## Related
- [Home](https://sentryxmonitor.com/)