Question

Difficulty: EasyVirtual Network Connectivity and Routing

An enterprise environment uses a hub-and-spoke topology. The hub virtual network is `vnet-hub-prod` (address space 10.1.0.0/1610.1.0.0/16) and hosts a network virtual appliance (NVA) at 10.1.0.410.1.0.4. Two spoke virtual networks are peered only to the hub: `vnet-spoke-web` (address space 10.2.0.0/1610.2.0.0/16) and `vnet-spoke-data` (address space 10.3.0.0/1610.3.0.0/16). You need to route all traffic between the two spokes through the NVA without overriding the default routing for communication within each spoke's own address space. Which two configurations should you implement?

  1. In the route table associated with the subnets in `vnet-spoke-web`, add a route for 10.3.0.0/1610.3.0.0/16 with a next hop of Virtual Appliance at 10.1.0.410.1.0.4.Answer
  2. In the route table associated with the subnets in `vnet-spoke-data`, add a route for 10.2.0.0/1610.2.0.0/16 with a next hop of Virtual Appliance at 10.1.0.410.1.0.4.Answer
  3. C
    In the route table associated with the subnets in `vnet-spoke-web`, add a route for 10.2.0.0/1610.2.0.0/16 with a next hop of Virtual Appliance at 10.1.0.410.1.0.4.
  4. D
    In the route table associated with the subnets in `vnet-spoke-data`, add a route for 10.3.0.0/1610.3.0.0/16 with a next hop of Virtual Appliance at 10.1.0.410.1.0.4.

Answer

To route inter-spoke traffic through the NVA, you must add a route for the remote spoke's address prefix (10.3.0.0/1610.3.0.0/16 in the web spoke, and 10.2.0.0/1610.2.0.0/16 in the data spoke) with a next hop pointing to the NVA's IP address. You must avoid creating user-defined routes for a spoke's own local address prefix, as doing so overrides the default system route for the local virtual network and disrupts internal communication.
To route transit traffic between the two spoke virtual networks through the NVA, you must define routes for the non-local spoke prefixes. Thus, the route table for the web spoke needs a route for the database spoke prefix (10.3.0.0/1610.3.0.0/16), and the route table for the database spoke needs a route for the web spoke prefix (10.2.0.0/1610.2.0.0/16). Both routes must point to the NVA's IP address at 10.1.0.410.1.0.4. This setup ensures that inter-spoke traffic is routed through the NVA, while local traffic within each spoke is handled by the default system route.

Step-by-Step Solution

1
Identify the target address prefix for outbound inter-spoke traffic originating from the web spoke.
The target prefix is the database spoke's address space: 10.3.0.0/1610.3.0.0/16.
This target prefix is used to steer traffic destined for the other spoke towards the NVA.
2
Identify the target address prefix for outbound inter-spoke traffic originating from the database spoke.
The target prefix is the web spoke's address space: 10.2.0.0/1610.2.0.0/16.
This target prefix is used to steer traffic returning or originating from the database spoke towards the NVA.
3
Configure the next hop type and IP address for both route definitions.
The next hop type is set to Virtual Appliance, and the next hop IP address is set to 10.1.0.410.1.0.4.
This directs traffic to the NVA hosted in the hub virtual network instead of using default direct routing.

Key Concept

User-Defined Routes and Default System Route Overrides
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