In Routing design for a two-tier topology between the data center and other parts of the network, select the best option from below

Question

Options

• AYou should not use VSX LAGs for these connections
• BDon't use Layer 3 links
• CEstablish point-to-point links using individual /29 subnets
• DSet up each link as an L3 interface or routed-only port (ROP)

• A
  4% (1)
• C
  4% (1)
• D
  92% (22)

Explanation

Setting up each link as an L3 interface or routed-only port (ROP) is correct because two-tier topology uplinks between the data center and the rest of the network benefit most from pure routing - each link runs a routing protocol adjacency, enabling ECMP load balancing, fast reconvergence, and eliminating Layer 2 loop risks entirely. ROPs are purpose-built for exactly this role: they forward only routed traffic with no bridging overhead.

Why the distractors are wrong:

• A is incorrect because VSX LAGs are appropriate for certain connections in this topology (e.g., dual-homed server links); blanket avoidance is bad advice.
• B is the opposite of best practice - Layer 3 links are preferred over Layer 2 for data center uplinks precisely because they avoid STP complexity and enable routing protocol control.
• C is wrong on the subnet size: point-to-point routed links should use /30 or /31 subnets (2 usable addresses), not /29 (6 usable), which wastes address space without benefit.

Memory tip: Think "uplinks go up to Layer 3." In a two-tier design, the moment traffic leaves the data center tier heading "up" to the rest of the network, every link should be a routed interface - no Layer 2 stretching, no STP, just routing. If you see /29 on a point-to-point link, that's a red flag.

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