What DNS Actually Does
The Domain Name System translates human-readable domain names into IP addresses that computers use to communicate. When you type example.com into your browser, your device cannot connect to a server using that name. It needs the IP address, like 93.184.216.34. DNS performs this translation through a distributed hierarchy of servers, starting with your local resolver and ending with the authoritative nameserver for that domain.
The process involves five steps: your browser checks its local cache, your operating system checks its cache, your router checks its cache, your ISP's recursive resolver checks its cache, and if nothing is cached, the resolver queries the root nameservers, then the TLD nameservers (.com, .org, .net), then the authoritative nameserver for the domain. Each step narrows down the answer until the final IP address returns to your device.
Essential DNS Record Types
A records map a domain to an IPv4 address. example.com A 93.184.216.34 tells DNS servers that example.com resolves to the IPv4 address 93.184.216.34. Every domain needs at least one A record to be reachable over IPv4, which remains the dominant protocol for web traffic.
AAAA records map a domain to an IPv6 address. The quadruple A reflects that IPv6 addresses are four times longer than IPv4 (128 bits vs 32 bits). example.com AAAA 2606:2800:220:1:248:1893:25c8:1946 provides the IPv6 equivalent. Dual-stack sites configure both A and AAAA records so clients can connect using whichever protocol their network supports.
CNAME records create an alias from one domain to another. www.example.com CNAME example.com means that when DNS resolves www.example.com, it first resolves example.com, then returns that IP address. CNAMEs are commonly used to point www to the root domain, or to point a domain to a hosting provider's load balancer.
MX records direct email to the correct mail servers. example.com MX 10 mail1.example.com means email for example.com should go to mail1.example.com with priority 10. Lower numbers indicate higher priority. A second MX record with priority 20 serves as a backup if the primary server is unreachable.
TXT records store arbitrary text data. They are used for email authentication (SPF, DKIM, DMARC), domain verification (Google Search Console, Microsoft 365), and SSL certificate validation. A typical SPF record looks like v=spf1 include:_spf.google.com ~all, telling receiving mail servers which servers are authorized to send email on behalf of your domain.
NS records delegate your domain to specific nameservers. example.com NS ns1.dnsprovider.com means that ns1.dnsprovider.com is authoritative for DNS queries about example.com. Changing NS records transfers DNS management to a different provider, which is what happens when you transfer a domain or switch DNS providers.
DNS Resolution Step by Step
Trace a complete DNS resolution by using the dig command with the +trace option. This shows every query made from root to authoritative:
dig +trace example.com
# Output shows:
# . (root) -> com. nameservers
# com. -> example.com. authoritative nameservers
# example.com. -> 93.184.216.34 (final answer)The dig command without +trace shows the final answer and the chain of nameservers used. The ANSWER SECTION contains the resolved IP address. The AUTHORITY SECTION shows which nameserver provided the answer. The ADDITIONAL SECTION contains IP addresses for those nameservers, saving a follow-up query.
dig example.com
;; ANSWER SECTION:
example.com. 3600 IN A 93.184.216.34
;; AUTHORITY SECTION:
example.com. 3600 IN NS a.iana-servers.net.TTL and Propagation
Time To Live (TTL) specifies how long DNS resolvers should cache a record before requesting a fresh copy. A TTL of 3600 means resolvers cache the answer for one hour. After that hour, the resolver re-queries the authoritative nameserver. Lower TTLs mean faster propagation of changes but more queries hitting your nameservers.
When you change a DNS record (updating an IP address, adding a new MX record), the change must propagate across all caching resolvers worldwide. A TTL of 86400 (24 hours) means the change may take up to 24 hours to reach all users. Before making DNS changes, reduce the TTL to 300 (5 minutes) at least 24-48 hours before the change. This ensures that when you make the actual change, all resolvers refresh their cache quickly.
# Before changing IP: lower TTL first
# Wait for old TTL to expire, then change:
example.com A 93.184.216.34 TTL=300 # Lower TTL
# ... 24-48 hours later ...
example.com A 93.184.216.99 TTL=3600 # Change IP, restore normal TTLUsing dig and nslookup for Diagnostics
nslookup provides quick DNS lookups for troubleshooting. It shows which nameserver answered the query and what records exist for a domain:
nslookup example.com
# Shows: Server (which resolver answered), Address, and the resolved IP
nslookup -type=MX example.com
# Shows all mail exchange records
nslookup -type=TXT example.com
# Shows SPF, DKIM, and other TXT recordsdig provides more detailed output than nslookup. Use it for comprehensive DNS debugging:
# Check specific record types
dig example.com A +short # Just the IP address
dig example.com MX +short # Just mail servers
dig example.com TXT +short # Just text records
dig example.com NS +short # Just nameservers
# Query a specific nameserver directly
dig @ns1.example.com example.com
# Check DNSSEC validation
dig example.com +dnssecOur DNS lookup tool performs comprehensive DNS resolution checks across multiple record types, displaying the full chain of records that affect your domain's email, web traffic, and authentication systems.
DNS Providers and Management
Your DNS provider operates the authoritative nameservers for your domain. Major providers include Cloudflare (free tier with DDoS protection), Google Cloud DNS (low-latency global anycast), AWS Route 53 (integration with AWS services), and traditional registrars like GoDaddy and Namecheap.
Cloudflare's free tier provides unlimited DNS records, DDoS protection, and a global anycast network that answers queries from the nearest data center. Their API allows programmatic DNS management, which is essential for automated certificate issuance and dynamic infrastructure:
# Cloudflare API: update DNS record
curl -X PATCH "https://api.cloudflare.com/client/v4/zones/ZONE_ID/dns_records/RECORD_ID" \
-H "Authorization: Bearer API_TOKEN" \
-H "Content-Type: application/json" \
--data '{"type":"A","name":"example.com","content":"93.184.216.99","ttl":300}'Use our DNS lookup tool to audit your domain's complete DNS configuration. Verify that all record types are correctly configured, TTL values are appropriate, and no stale records exist from previous hosting configurations that could route traffic to incorrect servers.