What is a DNS lookup and what does it tell you?

A DNS (Domain Name System) lookup translates a domain name like "example.com" into the IP addresses and configuration records that computers use to connect. A lookup reveals: A records (IPv4 addresses), AAAA records (IPv6), MX records (mail servers), CNAME records (aliases), TXT records (verification and SPF/DKIM email authentication), NS records (nameservers), and TTL values.

How long does DNS propagation take?

DNS propagation typically takes 1–48 hours after you make a DNS change, though most changes are visible globally within 1–4 hours. The delay exists because DNS resolvers around the world cache records for their TTL (Time To Live) duration. If your old record had a TTL of 24 hours, it can take up to 24 hours for all resolvers to pick up the change. Lowering TTL before planned changes speeds propagation.

What is the difference between an A record and a CNAME record?

An A record maps a domain name directly to an IPv4 address (e.g. example.com → 93.184.216.34). A CNAME (Canonical Name) record maps a domain name to another domain name, which is then resolved to an IP. CNAMEs allow you to point subdomains to services (e.g. shop.example.com → myshop.shopify.com) without updating IPs manually. You cannot have a CNAME on the root domain (@) — only on subdomains.

What are MX records and how do they work?

MX (Mail Exchanger) records tell the internet which mail servers accept email for your domain. When someone sends an email to you@example.com, their mail server looks up example.com's MX records to find where to deliver the message. MX records have a priority number — lower numbers are tried first. Most domains have two MX records: a primary (lower priority number) and a backup (higher number).

How to Check DNS Records Online — A Practical Guide (No Command Line)

What Is DNS?

DNS (Domain Name System) is the internet's address book. When you type a domain name into a browser (e.g., example.com), your computer queries a DNS server to translate that name into an IP address (e.g., 93.184.216.34) — the actual numeric address of the server. This translation happens in milliseconds, invisibly, every time you visit any website. DNS is also used for email routing, domain verification, content delivery networks, and security (SPF, DKIM, DMARC records for email authentication).

DNS Record Types Explained

There are several types of DNS records, each serving a different purpose. A record (Address): Maps a domain to an IPv4 address (e.g., example.com → 93.184.216.34). AAAA record: Maps a domain to an IPv6 address. MX record (Mail Exchange): Specifies which mail servers handle email for a domain. Essential for diagnosing email delivery problems. CNAME record (Canonical Name): An alias that points one domain name to another (e.g., www.example.com → example.com). TXT record: Stores arbitrary text, used for domain verification, SPF records (which mail servers can send email for a domain), DKIM keys, and DMARC policies. NS record (Name Server): Specifies which DNS servers are authoritative for a domain. SOA record (Start of Authority): Contains administrative information about a zone, including the primary nameserver and contact email.

When Do You Need to Check DNS Records?

DNS lookups are essential for several common scenarios: (1) Troubleshooting email delivery — if emails aren't arriving, check the MX records and SPF/DKIM TXT records. (2) Verifying domain ownership for services like Google Search Console, which ask you to add a TXT record as proof. (3) Diagnosing propagation — after updating DNS records, checking whether changes have propagated globally. (4) Setting up a custom domain for a website, email, or service. (5) Security auditing — checking whether DMARC and SPF records are correctly configured to prevent email spoofing. (6) Debugging CDN and load balancer configurations.

How to Use the Free DNS Lookup Tool

The DNS Lookup tool at allio.tools/tools/web/dns-lookup/ lets you query any record type for any domain directly in your browser. Enter a domain name (e.g., example.com), select the record type you want to check (A, MX, TXT, CNAME, NS, or All), and click Look Up. Results appear within seconds, showing all matching records with their current values and TTL (time to live). No command line knowledge is required — everything the terminal tool 'nslookup' or 'dig' does is available through this interface.

Understanding TTL (Time to Live)

Every DNS record has a TTL value — the number of seconds that DNS resolvers and browsers should cache the record before re-querying. Common TTL values: 300 seconds (5 minutes): used during transitions or when records change frequently. 3600 seconds (1 hour): a common default for most records. 86400 seconds (24 hours): used for stable, rarely changed records. When you update a DNS record, changes propagate gradually as cached entries expire across resolvers worldwide. If a record had a TTL of 86400 (24 hours), DNS propagation can take up to 24 hours — though it's usually much faster in practice.

Email DNS Records: SPF, DKIM, and DMARC

Three TXT record types are critical for email deliverability and security. SPF (Sender Policy Framework): specifies which mail servers are authorised to send email for your domain. Format: 'v=spf1 include:_spf.google.com ~all'. DKIM (DomainKeys Identified Mail): a digital signature system that proves an email was sent from an authorised server and hasn't been modified in transit. Appears as a TXT record at a subdomain like mail._domainkey.yourdomain.com. DMARC (Domain-based Message Authentication, Reporting & Conformance): tells receiving mail servers what to do with emails that fail SPF or DKIM checks (quarantine, reject, or allow). Appears as a TXT record at _dmarc.yourdomain.com. If your emails are going to spam, checking these three record types is the first diagnostic step.

Command-Line Alternative: dig and nslookup

If you prefer the terminal, 'dig' (macOS/Linux) and 'nslookup' (Windows) do the same thing. Examples: dig example.com A (look up A record). dig example.com MX (look up MX record). dig example.com TXT (look up TXT records). nslookup -type=mx example.com (Windows equivalent). The browser-based tool at allio.tools is faster for quick lookups and doesn't require opening a terminal or remembering syntax.