LPIC-1 Essential System Services and Networking Practice Question
An administrator is configuring a DHCP server to assign IP addresses to clients in the 192.168.10.0/24 subnet. The server should provide the default gateway as 192.168.10.1 and DNS server as 8.8.8.8. Which option in /etc/dhcp/dhcpd.conf defines the default gateway?
⚠ Common exam trap
Watch out — candidates often confuse the `option routers` directive with `option domain-name-servers` or `option subnet-mask`, especially since all three are commonly used together in a subnet declaration, but only `option routers` sets the default gateway.
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
✓
option routers 192.168.10.1;
The `option routers` directive in the ISC DHCP server configuration file `/etc/dhcp/dhcpd.conf` explicitly defines the default gateway (router) that clients should use. This directive sends the Router Option (option 3) in the DHCPOFFER and DHCPACK messages, instructing clients to set their default route to the specified IP address.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
option subnet-mask 255.255.255.0;
Why it's wrong here
The subnet-mask option defines the network prefix length, not the router address, so clients learn 255.255.255.0 but no gateway. It is tempting because it is a mandatory scope option that must be present for the 192.168.10.0/24 subnet to function at all.
- ✓
option routers 192.168.10.1;
Why this is correct
`option routers` is the DHCP parameter that delivers the default gateway address to clients, satisfying the stem's requirement to advertise 192.168.10.1 as the gateway for the 192.168.10.0/24 subnet. The `routers` option maps directly to DHCP option 3, which clients interpret as their default route.
- ✗
option broadcast-address 192.168.10.255;
Why it's wrong here
The broadcast-address option supplies the subnet's broadcast address, not the gateway; clients would receive no router value. It is tempting because it is a valid subnet-scoped DHCP option that must be declared alongside the gateway in a working scope, so it appears in correct configurations.
- ✗
option domain-name-servers 8.8.8.8;
Why it's wrong here
The domain-name-servers option delivers DNS resolver addresses, so clients would receive 8.8.8.8 as DNS but no default gateway. It is tempting because it is the exact option that satisfies the DNS half of the requirement, and it sits in the same scope block as the gateway.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 402 original LPIC-1 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-1 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-1 exam.