Question

Difficulty: MediumConfigure Azure Firewall

A company implements security policies that require all egress internet traffic from a database subnet named `DB-Subnet` to be inspected by a firewall. You deploy an Azure Firewall to the same virtual network in a subnet named `AzureFirewallSubnet`. The private IP address of the firewall is 172.16.0.4172.16.0.4. You need to direct all outbound internet traffic from the databases to the firewall. Which configuration should you apply to the route table associated with `DB-Subnet`?

  1. A route for destination 0.0.0.0/00.0.0.0/0 with a next hop type of Virtual appliance and a next hop address of 172.16.0.4172.16.0.4Answer
  2. B
    A route for destination 0.0.0.0/00.0.0.0/0 with a next hop type of Virtual network gateway and a next hop address of 172.16.0.4172.16.0.4
  3. C
    A route for destination 0.0.0.0/00.0.0.0/0 with a next hop type of Virtual appliance and a next hop address set to the public IP address of the Azure Firewall
  4. D
    A route for destination 172.16.0.0/16172.16.0.0/16 with a next hop type of Virtual appliance and a next hop address of 172.16.0.4172.16.0.4 associated with the AzureFirewallSubnet

Answer

A route for destination 0.0.0.0/00.0.0.0/0 with a next hop type of Virtual appliance and a next hop address of 172.16.0.4172.16.0.4
To route all outbound internet traffic from a workload subnet through an Azure Firewall, you must define a default route (0.0.0.0/00.0.0.0/0) in a user-defined route table. The next hop type must be set to Virtual appliance, and the next hop IP address must match the firewall's private IP address (172.16.0.4172.16.0.4). This route table must then be associated with the workload subnet.

Step-by-Step Solution

1
Identify the target address prefix for outbound internet traffic.
The destination address prefix is 0.0.0.0/00.0.0.0/0.
The default route of 0.0.0.0/00.0.0.0/0 matches all outbound traffic directed to the internet.
2
Define the appropriate next hop type for Azure Firewall.
The next hop type is Virtual appliance.
Azure Firewall is a software-based network virtual appliance, so it must be configured with this next hop type in the route table.
3
Specify the next hop IP address.
The next hop IP address is set to the firewall's private IP of 172.16.0.4172.16.0.4.
Egress traffic inside the virtual network must be routed to the firewall's private interface.

Key Concept

Routing traffic through Azure Firewall using User-Defined Routes (UDRs)
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