—
Comprehensive and Detailed Explanation From Exact Extract:
According to Nokia 7750 SR OS Routing Protocols Guide (Static Routing section, Chapter 5: Configuring Static Routes):
“A static route is configured by specifying the destination prefix and the next-hop IP address. The next-hop IP address must be reachable via a directly connected interface.”
In this scenario:
The network R1 wants to reach is 139.120.121.0/24 (behind R2).
R1 can reach R2 directly via IP 138.120.199.2 (the next-hop).
Therefore, the correct static route configuration on R1 is:
configure router static-route 139.120.121.0/24 next-hop 138.120.199.2
Explanation of incorrect options:
Option B: Next-hop 138.120.199.1 is R1 itself, invalid.
Option C: Configures a route to R2's interface, not the target subnet.
Option D: Next-hop 139.120.121.2 is unreachable from R1 directly.
This command structure strictly follows the syntax and logic described in Nokia’s SR OS: Static Routing Configuration Guide and is aligned with standard Nokia service router configuration practices.