Which of the following statements about the system interface on the Nokia 7750 SR is FALSE?

The statement that the prefix length of the system interface's IP address must be /32 is false. While using a /32 prefix is the standard best practice and is what Nokia documentation describes for this special loopback interface, the Service Router Operating System (SR OS) does not strictly enforce this rule at the CLI. It is technically possible to configure a different prefix length. However, doing so is highly discouraged as it is logically incorrect for a host-specific loopback and can cause unpredictable behavior in routing and management. The absolute term "must" makes the statement factually incorrect because it is not a rigid system constraint.

A. The system interface is a special, software-only loopback interface. It is not tied to any physical hardware and provides a stable address for the router.
C. The system interface is a fundamental component of the SR OS. This interface context is always present and cannot be deleted, thus it exists by default.
D. By default, routing protocols like OSPF and BGP will use the IP address of the system interface as the router ID if a router ID is not explicitly configured.

1. Nokia 7750 SR OS Router Configuration Guide, Release 22.10.R1, Page 70, "Basic Configuration" section.

Reference for C: The description for the no interface command explicitly states: "The system interface cannot be deleted." This confirms the interface is a permanent, default entity.

2. Nokia 7750 SR OS Router Configuration Guide, Release 22.10.R1, Page 65, "System Interface" section.

Reference for A: This section states, "The system interface is a logical interface that is not associated with a physical port... The system interface is also referred to as the loopback interface."

3. Nokia 7750 SR OS Basic System Configuration Guide, Release 22.10.R1, Page 53, "Router ID" section.

Reference for D: This section states, "The router ID is by default the system interface IP address. If the system interface is not configured, the router ID is 0.0.0.0..."

4. Nokia 7750 SR OS Router Configuration Guide, Release 22.10.R1, Page 65, "System Interface" section.

Reference for B (as a descriptive best practice, not a constraint): The guide notes, "This address is a /32 address and is used as the router ID." The falsehood of statement B comes from the fact that this is a description of correct configuration, not a strictly enforced CLI rule, making the word "must" inaccurate. The other options are verifiably true system properties.