AZ-104 Implement and Manage Virtual Networking Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Add a second address prefix to the spoke VNet and keep the overlapping range.

  Why it's wrong here

  Adding a second address prefix to the spoke VNet does nothing to eliminate the original overlapping range; the hub's conflicting prefix still exists in the spoke's address space. Azure allows adding non-overlapping prefixes, but the existing overlap remains a hard failure for peering. You must first delete the overlapping address space (after ensuring no subnets use it) and then add a new non-overlapping prefix. Alternatively, you could redesign the hub's address space, but the spoke's overlapping prefix cannot coexist in the peering relationship.

  When this WOULD be correct

  This option would be correct if the spoke VNet had no address space overlap but needed to communicate with an additional on-premises network that uses an overlapping range. Adding a second prefix to the spoke VNet and configuring appropriate routes could enable connectivity without changing the original range.

• ✓

  Change the spoke VNet to a non-overlapping address space before peering.

  Why this is correct

  VNet peering enforces a hard constraint: the address spaces of peered VNets must not overlap, because overlapping ranges make IP traffic semantically ambiguous at L3. To fix the spoke, you must remove the conflicting prefix from its address space before adding a non-overlapping one. Ensure no existing subnets or resources are deployed in the overlapping range, since you cannot delete an address space that is currently in use. Only then can the hub-spoke peering establish successfully.

• ✗

  Enable gateway transit on the hub VNet before retrying peering.

  Why it's wrong here

  Enabling gateway transit on the hub will not satisfy peering's requirement for disjoint address spaces. Gateway transit, when enabled, lets a spoke inherit the hub's VPN/ExpressRoute gateway for outbound traffic, but it only configures route propagation for those gateway routes; it does not alter the spoke's address space. Overlapping address space prevents the peering link itself from being created, so the peering resource never exists to take advantage of gateway transit. You must resolve the CIDR conflict before any hub-spoke routing, including gateway transit, can occur.

  When this WOULD be correct

  If the question stated that the hub has a VPN gateway and the spoke needs internet access through the hub, enabling gateway transit on the hub and using the spoke as a gateway spoke would be correct. The spoke would then route traffic via the hub's gateway.

• ✗

  Create custom DNS records for the spoke VNet so the address ranges no longer conflict.

  Why it's wrong here

  Custom DNS records only map hostnames to IP addresses and have no effect on IP prefix overlap, which is what peering validation checks. The peering operation examines each VNet's address spaces for CIDR collisions using Azure's network resource provider, not DNS resolution. Even if the DNS server resolved names to entirely different addresses, the actual VNet address space still contains the conflicting prefix, so the peering attempt will fail at provisioning time.

  When this WOULD be correct

  In a scenario where VNet peering succeeds but resources in the spoke cannot resolve names in the hub (or vice versa), and custom DNS servers are needed. For example, when using Azure-provided DNS and you need to resolve private IPs across peered VNets without Azure DNS resolution.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official AZ-104blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”