LCA Network Configuration & Troubleshooting 5

Question 1

Which command permanently sets the hostname to 'prod-server-01' on a systemd-based Linux system?

Accepted Answer

hostnamectl set-hostname prod-server-01

Answer

'hostnamectl set-hostname' updates /etc/hostname and the running system hostname atomically without requiring a reboot.

Question 2

A packet sent to 8.8.8.8 is dropped at hop 5 during a traceroute. What does this mean?

Accepted Answer

ICMP is blocked at hop 5, but the destination may still be reachable

Answer

Many routers deprioritize or block ICMP TTL-exceeded responses, so a traceroute timeout at a hop doesn't mean the destination is unreachable.

Question 3

Which command creates a VLAN interface tagged as VLAN 100 on top of eth0?

Accepted Answer

ip link add link eth0 name eth0.100 type vlan id 100

Answer

'ip link add link eth0 name eth0.100 type vlan id 100' creates an 802.1Q VLAN subinterface using iproute2.

Question 4

What does the 'nft list ruleset' command do?

Accepted Answer

Displays the complete nftables ruleset including tables, chains, and rules

Answer

'nft list ruleset' outputs the full nftables configuration including all tables, chains, and rules in a readable format.

Question 5

A DHCP client is not receiving an IP address. After confirming the DHCP server is running, what should you check next on the client?

Accepted Answer

Whether the client's NIC is up and sending DHCPDISCOVER broadcasts

Answer

DHCP begins with the client broadcasting DHCPDISCOVER; verifying the NIC is up and the broadcast is sent confirms the client side is working.

(LCA) Certified Linux Administrator Practice Test