DNS translates names to addresses in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How DNS Resolves a Website Name

Imagine you want to visit a website by typing its name in your browser. Which step correctly describes how DNS helps your computer find the website's address?

A DNS creates a new website name for your computer to use.

B DNS stores the website's content and sends it directly to your browser.

C DNS blocks unknown website names to protect your computer.

D DNS converts the website name into an IP address so your computer can connect to the right server.

💡 Hint

Think about what your computer needs to connect to a website: a number called an IP address.

DNS stands for Domain Name System. It acts like a phone book that translates website names (like example.com) into IP addresses (like 192.0.2.1) so your computer knows where to go.

❓ trace

intermediate

Trace the DNS Lookup Process

Follow the steps below and choose the correct order in which DNS resolves a website name to an IP address.

A 1,2,4,3,5,6

B 1,3,2,4,5,6

C 1,2,3,4,5,6

D 1,2,3,5,4,6

💡 Hint

Think about the hierarchy from local to root to TLD to authoritative servers.

The DNS lookup starts at your computer, goes to the local resolver, then root servers, then TLD servers, then authoritative servers, and finally back to your computer with the IP address.

❓ identification

advanced

Identify the DNS Record Type

Which DNS record type is responsible for translating a domain name like example.com into an IPv4 address?

A CNAME record

B A record

C MX record

D TXT record

💡 Hint

Think about the record that holds the IP address for a domain.

An A record maps a domain name to an IPv4 address. MX records are for mail servers, CNAME for aliases, and TXT for text information.

❓ Comparison

advanced

Compare DNS and Hosts File

Which statement correctly compares DNS and the hosts file on a computer?

A DNS is a global system for name resolution; hosts file is a local file that can override DNS.

B DNS stores website content; hosts file stores IP addresses globally.

C Hosts file is used only for email; DNS is used only for websites.

D DNS and hosts file both store IP addresses but hosts file is faster because it is online.

💡 Hint

Think about where each system works: local computer vs internet-wide.

The hosts file is a local file on your computer that can map names to IP addresses and override DNS lookups. DNS is a distributed system used globally.

🚀 Application

expert

Diagnose a DNS Resolution Problem

You type a website name in your browser but get an error saying the site cannot be reached. You run a command to check DNS resolution and get no IP address returned. Which of the following is the most likely cause?

A The DNS server is down or unreachable.

B The website's server is turned off.

C Your browser cache is full.

D Your computer's screen resolution is too low.

💡 Hint

If DNS lookup fails, the problem is usually with the DNS server or network.

If DNS cannot return an IP address, it often means the DNS server is not responding or your computer cannot reach it. The website server being off would cause a different error after IP resolution.

Practice

1. What is the main purpose of DNS (Domain Name System)?

easy

A. To speed up internet connection

B. To store website images

C. To translate website names into IP addresses

D. To block unwanted websites

Solution

1. Step 1: Understand what DNS does

   DNS converts easy-to-remember website names into numbers called IP addresses that computers use.

2. Step 2: Identify the correct purpose

   Among the options, only translating names to IP addresses matches DNS's main role.

3. Final Answer:

   To translate website names into IP addresses -> Option C

4. Quick Check:

   DNS = Name to IP translation [OK]

Hint: DNS changes names to numbers for computers [OK]

Common Mistakes:

• Thinking DNS stores website content
• Confusing DNS with internet speed tools
• Believing DNS blocks websites

2. Which of the following is the correct format of an IP address that DNS translates to?

easy

A. 192.168.1.1

B. example@domain

C. www.example.com

D. http://example

Solution

1. Step 1: Identify IP address format

   IP addresses are numeric and separated by dots, like 192.168.1.1.

2. Step 2: Match options to IP format

   Only 192.168.1.1 matches the numeric dotted format of an IP address.

3. Final Answer:

   192.168.1.1 -> Option A

4. Quick Check:

   IP address = numeric with dots [OK]

Hint: IP addresses are numbers separated by dots [OK]

Common Mistakes:

• Choosing website names instead of IPs
• Confusing URLs with IP addresses
• Selecting email-like formats

3. Consider this flowchart of DNS resolution:



If the DNS server does not have the IP address cached, what is the next step?

medium

A. Restart the computer

B. Return an error to the user

C. Directly connect to the website

D. Query the root DNS servers

Solution

1. Step 1: Understand DNS cache miss

   If the DNS server lacks the IP address, it must ask higher-level servers for help.

2. Step 2: Identify the next query target

   The next step is to query root DNS servers to find the authoritative server for the domain.

3. Final Answer:

   Query the root DNS servers -> Option D

4. Quick Check:

   Cache miss -> ask root servers [OK]

Hint: No cache? Ask root DNS servers next [OK]

Common Mistakes:

• Thinking DNS returns error immediately
• Trying to connect without IP
• Restarting computer unnecessarily

4. A user tries to visit www.example.com but gets an error saying 'DNS server not found'. What is the most likely cause?

medium

A. The DNS server address is incorrect or unreachable

B. The website is down

C. The user's computer has no internet cable plugged in

D. The website name is misspelled

Solution

1. Step 1: Analyze the error message

   'DNS server not found' means the computer cannot reach the DNS server to translate the name.

2. Step 2: Identify the cause

   This usually happens if the DNS server address is wrong or the server is unreachable, not because the website is down or misspelled.

3. Final Answer:

   The DNS server address is incorrect or unreachable -> Option A

4. Quick Check:

   DNS server unreachable -> error [OK]

Hint: DNS errors mean server address issues [OK]

Common Mistakes:

• Assuming website is down
• Blaming internet cable without checking DNS
• Ignoring DNS server settings

5. You want to speed up your website loading by reducing DNS lookup time. Which method below applies DNS caching correctly?

hard

A. Change website names to random numbers

B. Store IP addresses of frequently visited websites locally for quick access

C. Use longer website names to avoid confusion

D. Disable DNS on your computer

Solution

1. Step 1: Understand DNS caching

   DNS caching saves IP addresses locally so the computer doesn't ask the DNS server every time.

2. Step 2: Identify the correct caching method

   Storing IPs of frequent sites locally speeds up loading by skipping repeated lookups.

3. Step 3: Eliminate wrong options

   Changing names to numbers or disabling DNS breaks the system; longer names don't help speed.

4. Final Answer:

   Store IP addresses of frequently visited websites locally for quick access -> Option B

5. Quick Check:

   DNS caching = local IP storage [OK]

Hint: Cache IPs locally to speed DNS lookups [OK]

Common Mistakes:

• Thinking changing names helps speed
• Disabling DNS to fix speed
• Using longer names to improve performance