LPIC-2 Advanced Networking Configuration Practice Question
Exhibit
Refer to the exhibit.
# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:11:22:33:44:55 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.100/24 brd 192.168.1.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::211:22ff:fe33:4455/64 scope link
valid_lft forever preferred_lft foreverWhich command would add the default gateway 192.168.1.1 to this interface?
⚠ Common exam trap
Test-takers frequently choose the legacy `route` command (Option C) out of habit, forgetting that the modern `ip` command is required for LPIC-2 exams, and they may overlook the necessity of specifying the interface (`dev eth0`) to avoid ambiguous routing when multiple network interfaces are present.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ip route add default via 192.168.1.1 dev eth0
The `ip route add default via 192.168.1.1 dev eth0` command explicitly specifies both the gateway address and the outgoing interface, which is necessary when multiple interfaces exist or when the kernel needs to resolve the next-hop without ambiguity. The `default` keyword is a shorthand for `0.0.0.0/0` in IPv4, and the `dev eth0` clause ensures the route is bound to the correct interface.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ip route add 0.0.0.0/0 via 192.168.1.1 dev eth0
Why it's wrong here
Uses the network prefix 0.0.0.0/0, which is technically valid for the default route, but the preferred syntax on Linux is to use the 'default' keyword for clarity and consistency. The LPIC-2 exam expects the 'default' notation, so this option is considered incorrect.
- ✓
ip route add default via 192.168.1.1 dev eth0
Why this is correct
It uses the modern `ip` command with the `default` keyword and explicitly specifies both the gateway and the outgoing interface (`dev eth0`), which is the recommended practice for adding a default gateway.
- ✗
route add default gw 192.168.1.1
Why it's wrong here
Uses the legacy `route` command, which is deprecated and may not be available in all distributions. Additionally, it does not specify the outgoing interface, which is required to avoid ambiguity when multiple interfaces exist.
- ✗
ip route add default via 192.168.1.1
Why it's wrong here
Missing the `dev eth0` clause, which explicitly binds the route to the correct interface. While it might work with a single interface, the specification is necessary for clarity and to prevent routing issues.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 practice question is part of Courseiva's free LPI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LPIC-2 exam.