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DNS & DHCP

Technology Fundamentals

DNS & DHCP

1 min readPublished 22 Jul 2026

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DNS and DHCP are the two services that make networks usable: DNS turns names into IP addresses, and DHCP hands out those addresses automatically.

Interactive explainer

How DNS Resolves a Name

From typing a web address to receiving an IP — step by step.

11. Check caches22. Recursive resolver33. Root & TLD servers44. Authoritative server55. Return & cache

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1. Check caches

Already known?

The browser and OS check their local DNS caches first. If the name is cached and not expired, the IP is returned instantly.

Check your understanding

1. What is checked first when resolving a name?

2. Which server returns the actual IP for a domain?

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The core idea

  • DNS resolves human-friendly names (missiora.com) into IP addresses.
  • DHCP automatically assigns IP, subnet mask, gateway and DNS to devices.
  • The DHCP process is DORA: Discover, Offer, Request, Acknowledge.
Interactive explainer

How DHCP Assigns an Address (DORA)

Discover, Offer, Request, Acknowledge — how a device gets its IP.

11. Discover22. Offer33. Request44. Acknowledge

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1. Discover

Client shouts.

A client with no IP broadcasts a DHCP Discover to find any DHCP server on the network.

Check your understanding

1. What is the correct DHCP order?

2. What does a 169.254.x.x address indicate?

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DNS & DHCPNetworking Fundamentals CompTIA Network+
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How it works in practice

  • nslookup/dig test DNS; ipconfig /release + /renew re-run DHCP.
  • A 169.254.x.x (APIPA) address means DHCP failed.
  • Wrong DNS settings cause 'can ping the IP but not the name' symptoms.

Common mistakes

  • Confusing DNS (naming) with DHCP (addressing).
  • Blaming the network when it's a stale DNS cache (TTL).
  • Overlapping DHCP scopes causing address conflicts.

Why it matters for your career

DNS and DHCP issues are among the most common real-world tickets — interviewers love the classic 'a user can't reach a website, walk me through it' question.

Technical interview questions

  1. What is the difference between DNS and DHCP?
  2. Walk me through the DHCP DORA process.
  3. What does a 169.254 address mean?

Practice questions

  1. What resolves names to IPs? (DNS)
  2. What is the DHCP order? (Discover, Offer, Request, Acknowledge)
  3. What assigns IPs automatically? (DHCP)

Where this fits in your networking journey

This is one concept in the Networking Fundamentals path, which leads into CompTIA Network+ and Cisco CCNA. When this clicks, review Dynamic Routing (OSPF & BGP) and continue with NAT.

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Interview Intelligence

How this topic actually shows up in interviews — and how to demonstrate you understand it.

Why employers ask about this

DNS/DHCP issues cause a huge share of 'the internet is down' tickets; interviewers test that you can isolate them.

Technical questions
What does DNS do?+

It resolves human-friendly names to IP addresses (and back).

What does DHCP do?+

It automatically assigns IP configuration (address, mask, gateway, DNS) to devices.

Behavioural questions
Explain what happens if DNS fails.+

Names won't resolve even though IPs still work — sites appear down but pinging an IP succeeds.

Real-world scenarios
“Users can reach a site by IP but not by name.”+

Expected answer: It's a DNS problem — check the resolver and records.

Common candidate mistakes
  • •Blaming connectivity when it's actually DNS.
  • •Confusing DHCP with DNS.
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Employability Intelligence

Where this knowledge takes you — the jobs, skills and certifications it feeds into.

Relevant roles
IT Support TechnicianNetwork Administrator
Skills you're proving
DNSDHCPName resolutionTroubleshooting
Recommended certifications
CompTIA Network+
Career progression

IT Support → Network Support → Network Administrator.

What employers expect

That you can quickly isolate DNS vs DHCP vs connectivity.

Frequently asked questions

What is dns & dhcp in networking?

DNS and DHCP are the two services that make networks usable: DNS turns names into IP addresses, and DHCP hands out those addresses automatically.

What is the difference between DNS and DHCP?

DNS resolves human-friendly names (missiora.com) into IP addresses. DHCP automatically assigns IP, subnet mask, gateway and DNS to devices.

Do I need this for Network+ or CCNA?

Yes — DNS & DHCP is a core concept in CompTIA Network+ and Cisco CCNA. Understanding it here first makes the certification material much easier.

Related guides

Networking Fundamentals: The Complete Free Vendor-Neutral GuideDynamic Routing: OSPF & BGPNAT ExplainedThe OSI Model Explained

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