How to Use a DNS Lookup Tool Effectively

Every website, email server, and cloud service depends on DNS (Domain Name System) to function. When you type a domain name into a browser, DNS translates that name into an IP address so your computer knows where to connect. When that translation breaks or returns stale data, websites go down, emails bounce, and services become unreachable.

Running a DNS lookup lets you see exactly what records are published for a domain. This is the first step in diagnosing connection problems, verifying a new configuration, or auditing a domain’s setup. Our DNS Lookup Tool returns results in seconds, complete with record values, TTL timers, and the raw JSON response.

This guide walks through each DNS record type, explains what it does, and shows you how to use lookup results to solve real problems.

What Happens During a DNS Lookup

When your browser needs to find the IP address for example.com, it sends a query to a DNS resolver (usually provided by your ISP or configured manually, like Google’s 8.8.8.8 or Cloudflare’s 1.1.1.1). The resolver checks its cache first. If it has a fresh answer, it returns immediately. If not, it asks the root nameservers, then the TLD (top-level domain) nameservers, and finally the domain’s authoritative nameservers. Each step narrows the search until the resolver gets a definitive answer.

The authoritative nameserver returns the requested record along with a TTL (Time to Live) value, which tells the resolver how long to cache that answer before asking again. This caching system is what makes DNS fast for billions of daily queries, but it’s also why changes don’t take effect instantly.

DNS Record Types Explained

A Records

The A record maps a domain name to an IPv4 address. This is the most common record type. When you look up example.com and get 93.184.216.34, that mapping comes from an A record. Most websites have at least one A record. Load-balanced sites may have multiple A records pointing to different servers, and the resolver rotates through them.

AAAA Records

AAAA records serve the same purpose as A records but for IPv6 addresses. An IPv6 address looks like 2606:2800:0220:0001:0248:1893:25c8:1946. As IPv4 addresses become scarce, more hosting providers and CDNs publish AAAA records alongside A records. If a device supports IPv6 and the domain has an AAAA record, the connection may use IPv6 by default.

MX Records

MX (Mail Exchanger) records tell other mail servers where to deliver email for a domain. Each MX record has a priority number: lower numbers mean higher priority. If the server at priority 10 is unreachable, the sender retries at priority 20.

For example, a domain using Google Workspace might have:

• Priority 1: aspmx.l.google.com
• Priority 5: alt1.aspmx.l.google.com
• Priority 5: alt2.aspmx.l.google.com

If a domain has no MX records at all, email sent to any address at that domain will bounce with a “no mail exchanger” error.

TXT Records

TXT records store arbitrary text strings. They have become the workaround for adding metadata to DNS that was never part of the original specification. The most common uses are:

• SPF (Sender Policy Framework): Starts with v=spf1 and lists which IP addresses and servers are allowed to send email on behalf of the domain. Receiving mail servers check SPF to detect spoofed senders.
• DKIM (DomainKeys Identified Mail): Stored at a selector subdomain like selector1._domainkey.example.com. Contains a public key used to verify that email messages were signed by the domain owner.
• DMARC: Stored at _dmarc.example.com. Tells receiving servers what to do with messages that fail SPF or DKIM checks (reject, quarantine, or allow).
• Domain verification: Services like Google Search Console, Microsoft 365, and various SaaS platforms ask you to add a specific TXT record to prove you own the domain.

CNAME Records

A CNAME (Canonical Name) record creates an alias from one domain name to another. Instead of pointing directly to an IP address, it says “go look up this other domain instead.” For example, www.example.com might be a CNAME pointing to example.com, or blog.example.com might be a CNAME pointing to a hosting provider like hosting.provider.com.

One strict rule: a CNAME can’t coexist with other record types on the same hostname. You can’t have both a CNAME and an MX record for example.com. This is why the apex domain (the bare domain without www) usually uses A records rather than CNAMEs. Some DNS providers offer “CNAME flattening” or “ALIAS records” to work around this limitation.

NS Records

NS (Name Server) records identify the authoritative DNS servers for a domain. These are the servers that hold the master copy of all DNS records for that domain. When you register a domain and point it to a DNS provider like Cloudflare, Route 53, or Namecheap DNS, you are setting the NS records at the registrar level.

Querying NS records tells you who controls a domain’s DNS. This is useful when troubleshooting — if the NS records point to the wrong provider, none of the other records will resolve correctly.

Troubleshooting Common DNS Issues

Website Not Loading After DNS Change

After updating an A record or CNAME, the old record may be cached by resolvers and browsers. Check the TTL of the old record: if it was set to 86400 (24 hours), resolvers may serve the stale answer for up to a day. Use the DNS Lookup Tool to query Google Public DNS and compare the result with what you expect. If Google shows the correct new record but your browser still shows the old site, flush your local DNS cache:

• Windows: ipconfig /flushdns
• macOS: sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
• Chrome: Visit chrome://net-internals/#dns and click “Clear host cache”

Emails Bouncing or Going to Spam

Start by looking up the MX records for the domain. If they are missing or point to a decommissioned server, emails will bounce. Next, check TXT records for SPF. If the SPF record doesn’t include the IP addresses of your actual mail server, receiving servers may reject or flag your messages. Finally, verify DKIM by querying the TXT record at your selector subdomain.

A common mistake is having multiple SPF records for the same domain. The DNS specification says only one SPF record should exist per domain. If you see two v=spf1 entries, merge them into one.

Slow Propagation After Provider Migration

If you recently moved your DNS hosting from one provider to another, the old NS records at the registrar level may take up to 48 hours to fully propagate. During this window, some resolvers query the old provider and others query the new one. To minimize downtime:

1. Lower TTL values on all records to 300 seconds (5 minutes) at the old provider, at least 24 hours before the switch.
2. Recreate all records at the new provider.
3. Update the NS records at your registrar.
4. Wait for propagation — query the DNS Lookup Tool periodically to see when the new records appear.
5. After propagation completes, raise TTL values back to normal (3600 or higher).

Understanding TTL Values

TTL is measured in seconds. Common values and their meaning:

TTL	Duration	Typical Use
60	1 minute	During migrations, failover setups
300	5 minutes	Active development, frequent changes
3600	1 hour	Standard production records
86400	24 hours	Stable records that rarely change

Short TTLs mean changes propagate quickly, but resolvers send more queries to your authoritative nameserver. Long TTLs reduce query load but delay updates. For most production sites, 3600 seconds is a good balance.

Practical Tips for DNS Management

Document your records. Before making changes, run a lookup for every record type (A, AAAA, MX, TXT, CNAME, NS) and save the results. If something breaks, you can revert quickly.

Test before going live. When setting up a new mail provider or CDN, add the new records while keeping the old ones active. Verify the new records resolve correctly using the DNS Lookup Tool before removing the old configuration.

Watch for conflicting records. An A record and a CNAME on the same hostname will cause unpredictable behavior. Some DNS providers block this, but others silently allow it.

Use the IP Address Lookup tool alongside DNS. After confirming a domain resolves to a specific IP, use the IP Address Lookup Tool to verify that IP belongs to the expected hosting provider or CDN.

Frequently Asked Questions

Why do different DNS tools show different results for the same domain?

Each DNS resolver may have a different cached version of the record, depending on when it last queried the authoritative server and what TTL was set. Geographic location also matters for services using GeoDNS, which returns different IP addresses based on where the query originates.

How long does DNS propagation take?

Propagation depends on the TTL of the old records. If the previous TTL was 3600 seconds (1 hour), most resolvers will have the new data within 1-2 hours. If the old TTL was 86400 (24 hours), full propagation can take up to 48 hours because some resolvers cache aggressively beyond the stated TTL.

Can I have multiple A records for the same domain?

Yes. Multiple A records are commonly used for load balancing. DNS resolvers will rotate through the listed IP addresses, distributing traffic across multiple servers. This is called DNS round-robin.

What is the difference between a DNS lookup and a WHOIS lookup?

A DNS lookup queries the Domain Name System to find technical records (A, MX, TXT, etc.) that control how the domain functions. A WHOIS lookup queries the registrar database to find ownership information, including who registered the domain, when it expires, and contact details (if not privacy-protected).