What Is DNS? How the Domain Name System Works (Simple Guide)

The Domain Name System (DNS) is the internet's phone book. It translates human-readable domain names (like medhacloud.com) into the numeric IP addresses (like 104.21.32.1) that computers use to communicate with each other. Without DNS, you would need to memorize strings of numbers to visit every website.

Every time you type a URL into your browser, send an email, or open an app on your phone, DNS works behind the scenes to route your request to the correct server. It processes an estimated 1.1 trillion DNS queries per day globally, making it one of the most critical — and most targeted — components of the internet.

How DNS Works (Step by Step)

When you type "medhacloud.com" into your browser, here is exactly what happens in roughly 20-120 milliseconds:

Step 1: Browser Cache Check

Your browser first checks its own cache to see if it has recently looked up this domain. If you visited the site recently, the IP address is already stored and DNS resolution is instant.

Step 2: Operating System Cache

If the browser cache misses, the request goes to your operating system's DNS resolver cache (the "stub resolver"). Windows, macOS, and Linux all maintain a local DNS cache.

Step 3: Recursive Resolver

If the OS cache also misses, the query is sent to a recursive DNS resolver — usually operated by your ISP or a public DNS service like Google (8.8.8.8) or Cloudflare (1.1.1.1). This resolver does the heavy lifting.

Step 4: Root Name Server

The recursive resolver contacts one of the 13 root name server clusters that form the backbone of DNS. The root server does not know the IP address of medhacloud.com, but it knows which servers handle the .com top-level domain (TLD) and directs the resolver there.

Step 5: TLD Name Server

The .com TLD name server receives the query and responds with the authoritative name server responsible for the medhacloud.com domain.

Step 6: Authoritative Name Server

The authoritative name server has the actual DNS records for medhacloud.com. It responds with the IP address (for example, 104.21.32.1), and this answer travels back through the chain to your browser.

Step 7: Connection Established

Your browser now has the IP address and establishes a connection to the web server to load the page. The DNS result is cached at multiple levels (browser, OS, resolver) so future requests resolve instantly.

DNS Record Types Explained

DNS stores different types of records for different purposes. Understanding these is essential for managing business domains and troubleshooting issues.

Record Type	Purpose	Example
A Record	Maps a domain to an IPv4 address	medhacloud.com → 104.21.32.1
AAAA Record	Maps a domain to an IPv6 address	medhacloud.com → 2606:4700:3033::6815:2001
CNAME Record	Creates an alias pointing to another domain	www.medhacloud.com → medhacloud.com
MX Record	Directs email to mail servers	medhacloud.com → medhacloud-com.mail.protection.outlook.com
TXT Record	Stores text data for verification, SPF, DKIM, DMARC	v=spf1 include:spf.protection.outlook.com -all
NS Record	Specifies authoritative name servers for the domain	medhacloud.com → ns1.cloudflare.com
SOA Record	Contains administrative information about the domain zone	Primary name server, admin email, serial number
SRV Record	Specifies server for specific services	_sip._tcp.medhacloud.com → sipserver.medhacloud.com
PTR Record	Reverse DNS — maps IP address to domain name	104.21.32.1 → medhacloud.com

Critical Business Records

For any business running email, three TXT records are essential for email deliverability and security:

• SPF (Sender Policy Framework): Specifies which mail servers are authorized to send email for your domain. Prevents email spoofing.
• DKIM (DomainKeys Identified Mail): Adds a digital signature to outgoing emails proving they were not tampered with in transit.
• DMARC (Domain-based Message Authentication): Tells receiving servers what to do when SPF or DKIM checks fail (reject, quarantine, or none). Also provides reporting on authentication results.

Without proper SPF, DKIM, and DMARC records, your business emails are more likely to land in spam folders or be rejected entirely. As of 2024, Google and Yahoo require DMARC for bulk email senders.

How to Fix Common DNS Problems

Problem: Website Not Loading ("DNS_PROBE_FINISHED_NXDOMAIN")

Causes: Domain expired, DNS records deleted, misconfigured name servers, or local DNS cache corruption.

Fixes:

1. Flush your local DNS cache: ipconfig /flushdns (Windows) or sudo dscacheutil -flushcache (macOS)
2. Try a different DNS resolver (switch to 8.8.8.8 or 1.1.1.1)
3. Check domain registration status at your registrar
4. Verify A/CNAME records point to the correct server IP

Problem: Email Not Delivering

Causes: Incorrect MX records, missing SPF/DKIM/DMARC, or DNS propagation delay after changes.

Fixes:

1. Verify MX records point to your email provider (e.g., Microsoft 365, Google Workspace)
2. Check SPF record includes your email service
3. Use tools like MXToolbox or dmarcian to validate all email DNS records
4. Wait up to 48 hours for DNS changes to fully propagate

Problem: Slow DNS Resolution

Causes: Slow ISP DNS resolver, DNS server overload, or high TTL values preventing cache updates.

Fixes:

1. Switch to a faster public DNS resolver (Cloudflare 1.1.1.1 or Google 8.8.8.8)
2. Check DNS response times with nslookup or dig
3. Consider implementing DNS caching on your local network

Should You Turn DNS On or Off?

This question usually refers to specific DNS features, not DNS itself (you cannot use the internet without DNS). Here is what people typically mean:

• DNS over HTTPS (DoH): Encrypts DNS queries to prevent ISP snooping. Leave on for privacy.
• Private DNS on Android: Routes DNS through an encrypted connection. Leave on or set to a trusted provider.
• Smart DNS: Routes only DNS traffic through a different server (often for geo-restriction bypass). Turn on only if you need it; it does not provide security.
• DNS filtering (Pi-hole, NextDNS): Blocks ads and malicious domains at the DNS level. Recommended for businesses as a lightweight security layer.

DNS Security: Why DNS Matters for Business

DNS is a frequent target for cyberattacks because compromising DNS gives attackers control over where traffic goes. Key DNS-based threats include:

DNS Spoofing / Cache Poisoning

Attackers inject fraudulent DNS records into a resolver's cache, redirecting users to malicious sites that look identical to legitimate ones. Victims enter credentials on a fake login page without knowing they have been redirected.

DNS Tunneling

Malware encodes data within DNS queries and responses to exfiltrate data or establish command-and-control channels. Since DNS traffic is rarely inspected, this technique bypasses most firewalls.

DDoS Attacks on DNS

Flooding DNS servers with traffic to make websites unreachable. The 2016 Dyn attack took down Twitter, Netflix, Reddit, and hundreds of other major sites by overwhelming a single DNS provider.

Domain Hijacking

Gaining unauthorized access to a domain registrar account and modifying DNS records to redirect traffic. Often achieved through compromised credentials or social engineering of registrar support staff.

DNS Security Best Practices

• Enable DNSSEC: Digitally signs DNS responses to prevent spoofing and cache poisoning
• Use DNS filtering: Block access to known malicious domains at the DNS level (Cisco Umbrella, Infoblox, NextDNS)
• Monitor DNS traffic: Unusual query volumes or queries to suspicious domains can indicate malware or data exfiltration
• Implement DNS over HTTPS (DoH) or DNS over TLS (DoT): Encrypts DNS queries to prevent interception
• Use registrar lock: Prevents unauthorized domain transfers
• Enable two-factor authentication on domain registrar accounts

DNS for MSPs

For managed service providers, DNS management is a foundational service that touches every client. Common MSP DNS responsibilities include:

• Domain and DNS management: Managing DNS records for client domains across registrars (GoDaddy, Cloudflare, Namecheap)
• Email DNS configuration: Setting up and maintaining MX, SPF, DKIM, and DMARC records for Microsoft 365 and Google Workspace
• DNS security: Implementing DNS filtering to block malicious domains across all client networks
• Troubleshooting: Resolving DNS-related outages, email delivery failures, and website access issues
• Migration support: Updating DNS records during email migrations, website moves, and cloud transitions

DNS issues are among the most common support tickets for MSPs, and misconfigurations can have immediate business impact (email stops working, websites go down). Having certified network engineers on your team who understand DNS inside and out is critical for delivering reliable managed services.

How to Check DNS Settings

Several methods to verify DNS configuration:

Command Line

• Windows: nslookup medhacloud.com — shows the IP address and name server
• macOS/Linux: dig medhacloud.com — detailed DNS query output including TTL and record type
• All platforms: nslookup -type=MX medhacloud.com — check specific record types

Online Tools

• MXToolbox: Comprehensive DNS, email, and blacklist checking
• Google Admin Toolbox Dig: Google's DNS lookup tool
• DNSChecker.org: Check DNS propagation across multiple global locations
• dmarcian: Validate DMARC, SPF, and DKIM records

Frequently Asked Questions

What is DNS and why is it used?

DNS (Domain Name System) translates human-readable domain names like google.com into IP addresses like 142.250.80.46 that computers use to identify each other on the internet. It is used because humans remember words better than numbers. Without DNS, you would need to type numeric IP addresses for every website you visit.

How do I fix a DNS server problem?

Start by flushing your DNS cache (ipconfig /flushdns on Windows). Try switching to a public DNS resolver like Google (8.8.8.8) or Cloudflare (1.1.1.1). Check if the issue is isolated to one device or affects your entire network. For business DNS issues, verify your domain's DNS records at your registrar and check MX records if email is affected.

Should I turn DNS on or off?

You cannot turn DNS off and still use the internet. If the question is about DNS over HTTPS (DoH) or private DNS on your phone, leave these on for better privacy. If it is about DNS filtering services, turning these on adds a security layer that blocks malicious websites. The only DNS feature you might turn off is Smart DNS if you do not need geo-restriction bypass.

How to check DNS settings?

On Windows, open Command Prompt and type "nslookup yourdomain.com" to see the IP address your domain resolves to. For more detail, use "nslookup -type=any yourdomain.com" to see all DNS records. Online tools like MXToolbox.com provide comprehensive DNS analysis including MX, SPF, DKIM, and DMARC validation.

Key Takeaways

• DNS translates domain names to IP addresses — it is the internet's phone book and handles 1.1 trillion queries daily.
• A DNS lookup passes through browser cache, OS cache, recursive resolver, root server, TLD server, and authoritative server in ~20-120ms.
• Critical business DNS records include A, MX, SPF, DKIM, and DMARC — misconfigurations directly impact email deliverability and website access.
• DNS attacks (spoofing, tunneling, DDoS) are common — enable DNSSEC, DNS filtering, and DoH for protection.
• MSPs handle DNS as a core managed service — white-label network services provide certified engineers for DNS management at scale.