Route Tables & User Defined Routes
System routes, user defined routes and next hop selection for steering traffic through appliances and on-premises.
Readiness
0%
1h 50m baseline
Exam memorization points
- Azure creates system routes for the virtual network itself, for internet egress, and for private and peered address space.
- User defined routes override system routes of the same prefix, and the most specific prefix (longest match) always wins.
- Next hop types: Virtual network gateway, Virtual network, Internet, Virtual appliance, and None.
- A route table associates with a subnet, never with a virtual network or an individual NIC.
- Forced tunnelling to on-premises is a 0.0.0.0/0 route with a virtual network gateway next hop.
- BGP route propagation from a gateway can be disabled per route table when you need to guarantee UDR behaviour.
Traps & distractors
- Routing 0.0.0.0/0 to a virtual appliance without also adding a route for the virtual network and for Azure platform traffic, which breaks platform dependencies.
- Forgetting to enable IP forwarding on the appliance's NIC, which silently drops forwarded packets.
- Associating a route table with a virtual network instead of a subnet - the option does not exist.
- Expecting to delete system routes. Custom routes can only override them.
- Using a route table to filter traffic. Routes steer, they do not deny; use an NSG to deny.
Suggested lab
Force traffic through a network virtual appliance
Build the classic inspect-then-forward pattern and verify the effective route.
- 1Deploy a small Linux VM as the appliance in an appliance subnet and enable IP forwarding on its NIC.
- 2Create a route table with 0.0.0.0/0 next hop Virtual appliance pointing at the appliance's private IP.
- 3Associate the route table with the workload subnet and check Effective routes on a workload NIC.
- 4Add a route for the virtual network address space with next hop Virtual network so platform traffic is not sent to the appliance.
- 5Disable IP forwarding on the appliance NIC and confirm connectivity for the workload breaks.
Microsoft Learn
- Virtual network traffic routingdoc
- Search Microsoft Learn: user defined route next hop virtual appliance forced tunnelingsearch
Live Microsoft Learn ingestion is a Sprint 2 item; until then links are curated and the search fallback always resolves.
Status
No time invested yet. Baseline assumptions only.
Self-assessed mastery
0%
High priority
Strong exam value. Schedule this week.
- Exam importance80% × 30% = 24.0
Learner-agnostic frequency on the real exam (4/5).
- Blueprint weight78% × 25% = 19.4
This topic's domain carries 17.5% of the exam objectives.
- Dependency leverage0% × 20% = 0.0
Nothing else in the graph depends on this topic.
- Current gap100% × 25% = 25.0
Readiness is 0%, so 100% of the topic is still uncovered.
Exam Priority Score = 30% importance + 25% blueprint + 20% dependency + 25% gap. Importance is exam frequency, blueprint is the domain's official exam weight, dependency is how many later topics this one unlocks, and gap is how far you currently are from ready.
Unlocks next
Leaf topic - nothing depends on it.
Baseline study time
1h 50m
Complexity
4 / 5
Remaining to target
1h 34m
Status weight
0%
Topics: udr, route table, next hop, forced tunneling, nva, effective routes, bgp
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