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Zorluk: OrtaConfigure User-Defined Routes and Routing Tables

An organization has an Azure virtual network named `VNet-A` (10.50.0.0/1610.50.0.0/16) that contains three subnets:
- `Subnet-1` (10.50.1.0/2410.50.1.0/24)
- `Subnet-2` (10.50.2.0/2410.50.2.0/24)
- `Subnet-Security` (10.50.10.0/2410.50.10.0/24)

Azure automatically creates a default system route for the local virtual network (10.50.0.0/1610.50.0.0/16, next hop: Virtual network).

To control traffic, an administrator creates a route table named `RT-Prod` and associates it with `Subnet-1`. The route table contains the following user-defined routes (UDRs):
- Route1: Destination prefix 0.0.0.0/00.0.0.0/0, Next hop type: Virtual appliance, Next hop IP address: 10.50.10.410.50.10.4
- Route2: Destination prefix 10.50.2.0/2410.50.2.0/24, Next hop type: None

A virtual machine in `Subnet-1` attempts to connect to a database server at the IP address 10.50.2.5510.50.2.55 in `Subnet-2`.

How is this traffic routed?

  1. The traffic is dropped.Cevap
  2. B
    The traffic is routed to the virtual appliance at 10.50.10.410.50.10.4.
  3. C
    The traffic is routed directly to the database server via the virtual network local system route.
  4. D
    The traffic is routed to the default Internet gateway.

Cevap

The traffic is dropped.
The correct answer states that the traffic is dropped. When the virtual machine attempts to send traffic to the destination IP address 10.50.2.5510.50.2.55, Azure compares the destination against all active routes in the route table associated with the source subnet. The destination matches the user-defined route for 10.50.2.0/2410.50.2.0/24 (prefix length /24), the system local virtual network route for 10.50.0.0/1610.50.0.0/16 (prefix length /16), and the default route for 0.0.0.0/00.0.0.0/0 (prefix length /0). Following the Longest Prefix Match rule, the most specific route (10.50.2.0/2410.50.2.0/24) is selected. Since its next hop type is defined as None, the traffic is discarded.

Adım Adım Çözüm

1
Identify the target IP address and determine all matching route prefixes.
Target IP 10.50.2.5510.50.2.55 matches three prefixes: the virtual network local route (10.50.0.0/1610.50.0.0/16), the user-defined route Route2 (10.50.2.0/2410.50.2.0/24), and the default route Route1 (0.0.0.0/00.0.0.0/0).
This establishes the candidate routes that could be used to forward the traffic.
2
Apply the Longest Prefix Match (LPM) rule to select the active route.
The prefix 10.50.2.0/2410.50.2.0/24 has a length of 24, which is longer than both the virtual network prefix length of 16 and the default route prefix length of 0.
Azure's routing decision engine prioritizes routes with the most specific prefix matching the destination IP.
3
Identify the next hop type of the selected route to determine the final path.
The next hop type for Route2 (10.50.2.0/2410.50.2.0/24) is None, which causes the packets to be dropped.
A next hop type of None explicitly instructs the Azure virtual network to drop matching traffic instead of forwarding it.

Anahtar Kavram

Azure determines packet routing by selecting the route with the Longest Prefix Match (LPM). User-defined routes with more specific prefixes override standard system routes, and setting the next hop to None acts as a traffic filter.
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Konular

Configure User-Defined Routes and Routing Tables