You asked a network engineer to configure a new logical interface on a Juniper router. The interface must use the fourth usable host address from the 172.16.40.128/29 subnet. Which IP address is correct in this scenario?
In the Junos OS environment, precise IP addressing and subnet calculation are foundational for interface configuration. A /29 subnet mask (255.255.255.248) provides a total of 8 IP addresses. To identify the usable host range, we must first identify the network and broadcast addresses. For the subnet 172.16.40.128/29, the network address is 172.16.40.128. The broadcast address is the last address in the block, which is 172.16.40.135.
Following standard IPv4 conventions, the first and last addresses in a block are reserved for the network identity and the directed broadcast, respectively. This leaves 6 usable host addresses: 172.16.40.129 through 172.16.40.134. Counting sequentially from the beginning of the usable range: the first usable host is .129, the second is .130, the third is .131, and the fourth usable host is 172.16.40.132. Assigning this specific address ensures that the Packet Forwarding Engine can correctly route traffic within the intended segment. As a Senior Architect, it is critical to verify these boundaries when using the set interfaces unit 0 family inet address command to prevent address overlapping or the accidental assignment of reserved network/broadcast IDs.
Chosen Answer:
This is a voting comment (?). You can switch to a simple comment. It is better to Upvote an existing comment if you don't have anything to add.
Submit