SK0-004 · Question #425
While reviewing a network connectivity issue to a Linux server, the systems administrator issues the ifconfig command with the following results: According to the output above, which of the…
The correct answer is B. The adapter is not in an "UP" state. An ifconfig output missing the 'UP' flag in the interface status indicates the network adapter is disabled and cannot pass traffic.
Question
While reviewing a network connectivity issue to a Linux server, the systems administrator issues the ifconfig command with the following results:
According to the output above, which of the following is the problem?
Options
- AThe adapter is in "BROADCAST" mode
- BThe adapter is not in an "UP" state
- CThe broadcast address is incorrect
- DThe netmask is incorrectly configured
How the community answered
(20 responses)- A5% (1)
- B75% (15)
- C5% (1)
- D15% (3)
Why each option
An ifconfig output missing the 'UP' flag in the interface status indicates the network adapter is disabled and cannot pass traffic.
BROADCAST mode is a standard, expected flag for Ethernet interfaces and does not indicate a problem.
In Linux, the ifconfig command displays interface flags such as UP, BROADCAST, and RUNNING. If the 'UP' flag is absent from the output, the interface is administratively or physically down and will not send or receive network traffic, which directly explains the connectivity failure. The interface must be brought up using 'ifconfig <interface> up' or 'ip link set <interface> up'.
An incorrect broadcast address would cause broadcast traffic issues but would not prevent basic unicast network connectivity.
An incorrectly configured netmask would cause routing problems to certain subnets but would not completely disable the adapter as indicated by the output.
Concept tested: Linux ifconfig interface UP state diagnosis
Source: https://man7.org/linux/man-pages/man8/ifconfig.8.html
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