The answer is to run `dhclient -r eth0 && dhclient eth0`. This command releases the current DHCP lease and then immediately renews it, forcing the client to re-apply all options from the lease file, including the default gateway route that was correctly stored but not installed into the routing table. On the LPIC-2 exam, this scenario tests your understanding of how the DHCP client daemon applies lease options to the kernel’s routing table—a common pitfall is assuming a valid lease guarantees an active default route, when in fact the route may be missing due to a transient failure in the client’s option processing. The exam often presents this as a troubleshooting question where the lease file contains `option routers 192.168.1.1` but `ip route show` lacks a default gateway, and the trap is to restart the entire networking service or manually add the route instead of using the targeted release-and-renew cycle. Remember the mnemonic: “Release, then renew—don’t add the route by hand, let the lease command.”
LPIC-2 Network Client Management Practice Question
This LPIC-2 practice question tests your understanding of network client management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are troubleshooting a Linux client that is unable to connect to the internet. The client is configured to use DHCP on interface eth0. The output of 'ip addr show eth0' shows that the interface has an IP address 192.168.1.100/24, but there is no default gateway. The output of 'ip route show' shows only the local subnet route. The DHCP server is at 192.168.1.1 and is functioning correctly. You have verified that the DHCP client (dhclient) is running, and the lease file /var/lib/dhclient/dhclient-eth0.leases exists and contains option routers 192.168.1.1. Which of the following commands should you run to resolve the issue?
Why wrong: Restarting networking may disrupt other services and might not trigger a DHCP renewal if the interface is already configured.
B
ip route del default
Why wrong: This would only remove any existing default route, but there is no default route to remove, and it does not add one.
C
dhclient -r eth0 && dhclient eth0
This releases the current lease and obtains a new one, which should reinstate the default gateway from the DHCP server.
D
ip route add default via 192.168.1.1
Why wrong: While this would add a default route manually, it is not the appropriate resolution for a DHCP configuration issue; the route should be assigned automatically by DHCP.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
dhclient -r eth0 && dhclient eth0
Option C is correct because the DHCP client has already obtained a lease with the correct gateway (192.168.1.1), but the default route was not applied. Running `dhclient -r eth0` releases the current lease, and `dhclient eth0` renews it, forcing the client to re-apply all options from the lease, including the default gateway route. This is the standard way to reinitialize the interface's network configuration from the DHCP server without restarting the entire networking service.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
systemctl restart networking
Why it's wrong here
Restarting networking may disrupt other services and might not trigger a DHCP renewal if the interface is already configured.
✗
ip route del default
Why it's wrong here
This would only remove any existing default route, but there is no default route to remove, and it does not add one.
✓
dhclient -r eth0 && dhclient eth0
Why this is correct
This releases the current lease and obtains a new one, which should reinstate the default gateway from the DHCP server.
Related concept
Read the scenario before looking for a memorised answer.
✗
ip route add default via 192.168.1.1
Why it's wrong here
While this would add a default route manually, it is not the appropriate resolution for a DHCP configuration issue; the route should be assigned automatically by DHCP.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose the manual route addition (Option D) because it seems quick and effective, but the LPIC-2 exam expects you to understand that the proper troubleshooting step is to renew the DHCP lease to ensure all options are correctly applied, rather than applying a temporary fix that bypasses the DHCP client's configuration logic.
Detailed technical explanation
How to think about this question
When a DHCP client (dhclient) obtains a lease, it stores the options (including routers) in a lease file, but the actual application of routes is handled by the client's script (typically /etc/dhcp/dhclient-enter-hooks or the default client script). If the route was not applied due to a transient error or race condition, releasing and renewing the lease forces the client to re-execute the entire configuration process, including adding the default gateway. In real-world scenarios, this can occur after a network change or a misconfigured DHCP server that temporarily omitted the router option, but the lease file still contains the correct data.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Client Management — This question tests Network Client Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: dhclient -r eth0 && dhclient eth0 — Option C is correct because the DHCP client has already obtained a lease with the correct gateway (192.168.1.1), but the default route was not applied. Running `dhclient -r eth0` releases the current lease, and `dhclient eth0` renews it, forcing the client to re-apply all options from the lease, including the default gateway route. This is the standard way to reinitialize the interface's network configuration from the DHCP server without restarting the entire networking service.
What should I do if I get this LPIC-2 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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