ifconfig and ip addr in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the primary purpose of the ifconfig command?

The ifconfig command is used to display or configure network interfaces on a Linux system. It shows IP addresses, network masks, and interface status.

beginner

What does the ip addr command do?

The ip addr command shows detailed information about all network interfaces, including IP addresses, link status, and more. It is a modern replacement for ifconfig.

beginner

How do you display all network interfaces using ifconfig?

Simply type ifconfig without any arguments to list all active network interfaces and their details.

intermediate

How can you show both active and inactive interfaces using ip addr?

Use ip addr show or just ip addr. It lists all interfaces, whether active or inactive, with their IP addresses and status.

intermediate

Why is ip addr preferred over ifconfig in modern Linux systems?

ip addr is part of the newer iproute2 suite. It provides more detailed info, supports more features, and is actively maintained, unlike ifconfig which is deprecated.

Which command shows IP addresses and network interfaces on Linux?

A ls

B ifconfig

C cd

D mkdir

ifconfig displays network interfaces and IP addresses.

What is the modern replacement for ifconfig?

A ip addr

B netstat

C ping

D traceroute

ip addr is the modern command to show network interface info.

How do you show all network interfaces including inactive ones?

A ip addr show

B ifconfig -a

C ls -l

D ip link down

ip addr show and ifconfig -a both list all interfaces, active or inactive.

Which command is deprecated but still commonly used?

A ss

B ip addr

C ifconfig

D ip route

ifconfig is deprecated but still found on many systems.

What information does ip addr NOT show?

A IP addresses

B Interface status

C MAC addresses

D Routing table

ip addr shows addresses and status, but routing info is shown by ip route.

Explain the differences between ifconfig and ip addr commands.

Think about which command is older and which one is recommended now.

Describe how to check all network interfaces and their IP addresses on a Linux system.

Remember both commands can show interfaces but differ in details.

Practice

1. What is the main purpose of the ifconfig and ip addr commands in Linux?

easy

A. To manage user accounts

B. To edit text files in the system

C. To monitor CPU usage

D. To display network interface details and IP addresses

Solution

1. Step 1: Understand command purpose

   The commands ifconfig and ip addr are used to show details about network interfaces and their IP addresses.

2. Step 2: Eliminate unrelated options

   Options about editing files, managing users, or CPU monitoring do not relate to network interfaces.

3. Final Answer:

   To display network interface details and IP addresses -> Option D

4. Quick Check:

   Network info = C [OK]

Hint: Remember: both commands show network info, not files or users [OK]

Common Mistakes:

• Confusing network commands with file editing tools
• Thinking these commands manage users
• Assuming they monitor CPU or memory

2. Which of the following is the correct syntax to display all IP addresses using the ip command?

easy

A. ip address list all

B. ip show addr

C. ip addr show

D. ip display ip

Solution

1. Step 1: Recall correct command syntax

   The correct syntax to show IP addresses is ip addr show or simply ip addr.

2. Step 2: Check other options for errors

   Options B, C, and D use incorrect order or invalid keywords.

3. Final Answer:

   ip addr show -> Option C

4. Quick Check:

   Correct syntax = A [OK]

Hint: Remember: 'ip addr show' is the standard order [OK]

Common Mistakes:

• Swapping 'addr' and 'show' order
• Using invalid keywords like 'display' or 'list all'
• Adding unnecessary words

3. What will be the output of the command ifconfig eth0 if the interface eth0 is up with IP 192.168.1.10 and netmask 255.255.255.0?

medium

A. Shows interface eth0 details including IP 192.168.1.10 and netmask 255.255.255.0

B. Shows only the MAC address of eth0

C. Shows error: interface eth0 not found

D. Shows CPU usage statistics

Solution

1. Step 1: Understand ifconfig eth0 output

   This command displays detailed info about the eth0 interface, including IP address and netmask if the interface is up.

2. Step 2: Eliminate unrelated outputs

   It does not show only MAC address, CPU stats, or error if interface exists and is up.

3. Final Answer:

   Shows interface eth0 details including IP 192.168.1.10 and netmask 255.255.255.0 -> Option A

4. Quick Check:

   ifconfig eth0 shows IP and netmask = D [OK]

Hint: ifconfig with interface name shows full details [OK]

Common Mistakes:

• Expecting only MAC address output
• Assuming error if interface is active
• Confusing with CPU or system stats

4. You run ip addr show eth0 but get no output. What is the most likely reason?

medium

A. The eth0 interface does not exist or is down

B. You need to run the command as root

C. The command syntax is incorrect

D. The IP address is not assigned yet

Solution

1. Step 1: Analyze command behavior

   If ip addr show eth0 returns no output, it usually means the interface eth0 does not exist or is disabled.

2. Step 2: Check other options

   Running as root is not required to show interfaces; syntax is correct; lack of IP alone does not cause no output.

3. Final Answer:

   The eth0 interface does not exist or is down -> Option A

4. Quick Check:

   No output means interface missing/down = B [OK]

Hint: No output usually means interface missing or down [OK]

Common Mistakes:

• Assuming root is needed to view interfaces
• Thinking syntax is wrong
• Confusing no IP with no output

5. You want to write a script that checks if the interface eth1 has an IP address assigned using ip addr. Which command snippet correctly tests this?

hard

A. ifconfig eth1 | grep -q 'inet6 '; then echo 'IP assigned'; else echo 'No IP'; fi

B. if ip addr show eth1 | grep -q 'inet '; then echo 'IP assigned'; else echo 'No IP'; fi

C. ip addr show eth1 | grep -q 'ether '; then echo 'IP assigned'; else echo 'No IP'; fi

D. if ip link show eth1 | grep -q 'UP'; then echo 'IP assigned'; else echo 'No IP'; fi

Solution

1. Step 1: Identify correct IP address check

   The command ip addr show eth1 lists addresses; searching for 'inet ' finds IPv4 addresses assigned.

2. Step 2: Evaluate other options

   ifconfig eth1 | grep -q 'inet6 '; then echo 'IP assigned'; else echo 'No IP'; fi checks IPv6 with ifconfig but question asks for ip addr. ip addr show eth1 | grep -q 'ether '; then echo 'IP assigned'; else echo 'No IP'; fi looks for MAC address ('ether'), not IP. if ip link show eth1 | grep -q 'UP'; then echo 'IP assigned'; else echo 'No IP'; fi checks interface status, not IP assignment.

3. Final Answer:

   if ip addr show eth1 | grep -q 'inet '; then echo 'IP assigned'; else echo 'No IP'; fi -> Option B

4. Quick Check:

   Check 'inet ' in ip addr output = A [OK]

Hint: Search 'inet ' in ip addr output to find IPv4 address [OK]

Common Mistakes:

• Checking MAC address instead of IP
• Using ip link instead of ip addr
• Confusing IPv6 with IPv4 check