LPI
010-100 · Question #36
010-100 Question #36: Real Exam Question with Answer & Explanation
The correct answer is A. lo. The loopback interface 'lo' is the only network interface guaranteed to exist on every Linux system because it is created automatically by the kernel at boot, independent of any hardware.
Question
Which network interface always exists in a Linux system?
Options
- Alo
- Bsit0
- Cwlan0
- Dvlan0
- Eeth0
Explanation
The loopback interface 'lo' is the only network interface guaranteed to exist on every Linux system because it is created automatically by the kernel at boot, independent of any hardware.
Common mistakes.
- B. The 'sit0' interface is an IPv6-in-IPv4 tunnel device that is only present when the 'sit' kernel module is loaded, which does not happen on every Linux system by default.
- C. The 'wlan0' interface only exists when a compatible wireless network adapter is present in the system and its driver is loaded, so it is absent on systems without wireless hardware.
- D. The 'vlan0' interface is created only when VLAN tagging is explicitly configured by an administrator and is not automatically present on any standard Linux installation.
- E. The 'eth0' interface depends on the presence of a compatible wired Ethernet adapter, and on modern systems using predictable network interface naming the device may be named 'ens3', 'enp2s0', or similar rather than 'eth0'.
Concept tested. Linux loopback interface as universal network interface
Reference. https://www.kernel.org/doc/html/latest/networking/loopback.html
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