Azure Networking Interview Questions for Microsoft Azure
25 Azure Networking questions with answers for microsoft azure roles — 4 easy, 13 medium, 8 hard.
About Azure Networking
Design and troubleshoot Azure networks: VNets, subnets, NSGs, peering, user-defined routes, hub-spoke topology, Azure Firewall, NAT Gateway and private endpoints. Learn when to use Load Balancer, Application Gateway, Front Door or Traffic Manager, and how VPN Gateway and ExpressRoute connect on-premises sites. Network Watcher skills help you fix connectivity issues fast.
Sheet progressStart practicing
3 QUESTIONS FREESign up to unlock the full question bank and track your progress.Unlock every question and answer, then continue practising company-wise and package-wise.
A VNet is your private, isolated network in an Azure region, defined by one or more address spaces such as 10.10.0.0/16 and divided into subnets. Resources in a VNet communicate privately and Azure provides default routing between subnets and to the internet. VNets connect to each other with peering and to on-premises with VPN Gateway or ExpressRoute. Azure reserves five IP addresses in every subnet.
An NSG is a stateful packet filter with allow and deny rules on source, destination, port and protocol, processed by priority from 100 to 4096, lower number first. It attaches to a subnet, a NIC or both, and both must allow the traffic. Default rules allow VNet-to-VNet and outbound internet traffic and deny other inbound traffic. Service tags and application security groups simplify rules.
03
You are setting up Azure DNS for a new domain. What are the steps?
Create a public DNS zone in Azure DNS for the domain, note the four Azure name servers it shows, and update the NS records at your domain registrar to those servers. Add records such as an A alias record pointing to the Front Door or public IP and CNAME for www. Verify with nslookup. Apply a lock on the zone so records cannot be deleted accidentally.
04
How do you work with the security team when they reject your network design?
Situation: security rejected my design because the app used public endpoints for storage and SQL. Task: meet their standards without delaying launch. Action: I met them, listed their controls, and redesigned with private endpoints, Azure Firewall egress and WAF, then shared a diagram and cost impact. Result: they approved it in one review cycle, and the design became a reusable team template.
05
How do you document and hand over a network design to the operations team?
Situation: I designed a hub-spoke network that a separate operations team would run. Task: make sure they could support it without calling me. Action: I wrote a short design note with diagrams, IP plan, routing and firewall rule ownership, kept everything in Bicep, and ran two walkthrough sessions with troubleshooting exercises using Network Watcher. Result: they handled the first three incidents independently.
Peering connects two VNets over the Microsoft backbone with low latency, either in the same region or globally. Traffic stays private and is billed per GB. Peering is not transitive: if A peers with B and B peers with C, A cannot reach C. To route through a hub, use a network virtual appliance or Azure Firewall with user-defined routes, or use Azure Virtual WAN.
07
Compare Azure Load Balancer, Application Gateway, Front Door and Traffic Manager.
Load Balancer works at layer 4 (TCP/UDP) inside a region. Application Gateway is a regional layer 7 load balancer with path routing, TLS termination and an optional WAF. Front Door is a global layer 7 entry point with anycast, CDN caching and WAF. Traffic Manager is DNS-based global routing for any protocol. Use Front Door for global web apps and Load Balancer for non-HTTP traffic.
08
What is the difference between a VPN Gateway and ExpressRoute?
A VPN Gateway creates encrypted IPsec tunnels over the public internet, for site-to-site or point-to-site connections, and is quick and cheap to set up. ExpressRoute is a private dedicated connection through a connectivity provider with predictable latency and bandwidth up to 100 Gbps, but it does not encrypt by default. Many companies use ExpressRoute as primary and a VPN as backup.
UDRs are custom routes in a route table attached to a subnet, overriding Azure system routes. A common use is sending 0.0.0.0/0 from spoke subnets to Azure Firewall in the hub, with next hop type Virtual appliance, so all outbound traffic is inspected. Mistakes in UDRs are a top cause of connectivity issues, so check effective routes on the NIC when troubleshooting.
10
What is Azure Firewall and how is it different from an NSG?
Azure Firewall is a managed, stateful, centralised firewall with network and application rules, FQDN filtering, threat intelligence and, in the Premium SKU, TLS inspection and IDPS. NSGs are distributed basic filters on subnets and NICs. Typically NSGs control traffic within and between subnets, while Azure Firewall in a hub controls internet egress and cross-spoke traffic with central logging.
Azure DNS hosts public DNS zones on Microsoft's global name servers so you can manage records like A and CNAME with RBAC. Private DNS zones resolve names only inside linked VNets, used for internal names and private endpoints. For hybrid name resolution, Azure DNS Private Resolver lets on-premises DNS forward queries into Azure and Azure forward queries back on-premises without custom DNS VMs.
A NAT Gateway provides outbound internet connectivity for a subnet using one or more static public IPs. It gives a large pool of SNAT ports, avoiding the port exhaustion common with default outbound or Load Balancer outbound rules, and gives a fixed IP that partners can allowlist. Since default outbound access is being retired for new VNets, explicit outbound methods like NAT Gateway are recommended.
13
Create a VNet with two subnets and an NSG rule using Azure CLI.
IP flow verify tells you if an NSG rule allows or denies a specific packet and which rule matched. Next hop shows where routing sends traffic. Connection troubleshoot tests reachability from a VM to an endpoint. Effective security rules and effective routes show the combined result on a NIC. VNet flow logs record traffic for analysis with Traffic Analytics. Packet capture records traffic on a VM.
16
A VM in a spoke cannot reach a VM in another spoke. What could be wrong?
Peering is not transitive, so spoke to spoke traffic needs a route through the hub. Check that both spokes have UDRs pointing the other spoke's range to the hub firewall, that peerings allow forwarded traffic, and that firewall network rules allow the flow. Then check NSGs on both subnets and NICs and the guest OS firewall. Use Network Watcher next hop and IP flow verify to confirm.
17
Tell me about a time you fixed a networking issue under pressure.
Situation: after a firewall change, payment APIs in our spoke could not reach a partner endpoint. Task: restore traffic quickly. Action: I used Network Watcher next hop and firewall logs in Log Analytics, found the new rule collection had higher priority and denied the partner FQDN, and added an explicit allow. Result: service recovered in 25 minutes, and we added pipeline-based firewall rule reviews.
18
What is the difference between a service endpoint and a private endpoint?
A service endpoint extends the VNet identity to a PaaS service so its firewall can allow your subnet, but the service still uses its public IP. A private endpoint puts a private IP from your subnet on a specific resource instance, so traffic never needs the public endpoint and works from peered networks and on-premises. Private endpoints are preferred for strict security but need private DNS setup.
The hub VNet holds shared services: Azure Firewall, VPN or ExpressRoute gateways, Bastion and DNS resolvers. Each workload gets its own spoke VNet peered to the hub, with UDRs sending traffic through the firewall. This centralises security and connectivity while isolating workloads. For many regions and branches, Azure Virtual WAN provides a Microsoft-managed hub with automatic transit routing.
20
Create a route table that sends internet traffic to Azure Firewall.
Add a default route with next hop Virtual appliance pointing to the firewall private IP, then attach it to the spoke subnet:
az network route-table create -g rg-net -n rt-spoke1
az network route-table route create -g rg-net \
--route-table-name rt-spoke1 -n default-to-fw \
--address-prefix 0.0.0.0/0 \
--next-hop-type VirtualAppliance --next-hop-ip-address 10.0.1.4
az network vnet subnet update -g rg-net --vnet-name vnet-spoke1 \
-n snet-app --route-table rt-spoke1
21
How do you plan IP address space for VNets in an enterprise?
Allocate from a central IP plan that does not overlap with on-premises, other clouds or future acquisitions, because overlapping ranges cannot be peered or routed. Give each region a large block, for example 10.10.0.0/14, then carve /22 or /24 spokes. Size subnets for growth and remember AKS, App Gateway and private endpoints consume many IPs. Document allocations in an IPAM tool such as Azure Virtual Network Manager IPAM.
22
An App Service cannot connect to an Azure SQL database behind a private endpoint. How do you troubleshoot?
Confirm the app has regional VNet integration into a subnet that can reach the private endpoint subnet. Check DNS first: from the Kudu console, nslookup the SQL server name; it must resolve to the private IP through privatelink.database.windows.net linked to the VNet. Then check NSGs, UDRs sending traffic to a firewall that blocks port 1433, and whether SQL public access is disabled as expected.
23
Your company needs a reliable private link from its Pune datacenter to Azure. What do you propose?
Propose ExpressRoute through a provider at the Pune or Mumbai peering location with private peering into a hub VNet in Central India, sized for current and forecast bandwidth. Add a site-to-site VPN as a failover path, or a second ExpressRoute circuit at another peering location for higher resilience. Use BGP for route exchange, and encrypt traffic with MACsec or IPsec if compliance requires.
24
How would you protect a public web application from attacks like SQL injection and DDoS?
Put Azure Front Door Premium or Application Gateway with WAF in front of the app, using the managed Default Rule Set based on OWASP plus bot protection and rate limits. Enable Azure DDoS Network Protection on the VNet for layer 3 and 4 attacks on public IPs. Lock the app so it accepts traffic only from Front Door, using access restrictions with the service tag and the Front Door ID header.
25
Partners need to allowlist a fixed outbound IP from your AKS cluster. How do you do it?
Configure the cluster's outbound type as a managed or user-assigned NAT Gateway with a static public IP, or route egress through Azure Firewall using userDefinedRouting so all traffic leaves from the firewall's public IP. Share that IP with partners. NAT Gateway is simpler and gives many SNAT ports, while Azure Firewall adds FQDN filtering and logging for compliance.
Frequently asked questions
How important is Azure Networking in Microsoft Azure interviews?
Design and troubleshoot Azure networks: VNets, subnets, NSGs, peering, user-defined routes, hub-spoke topology, Azure Firewall, NAT Gateway and private endpoints. Learn when to use Load Balancer, Application Gateway, Front Door or Traffic Manager, and how VPN Gateway and ExpressRoute connect on-premises sites. Network Watcher skills help you fix connectivity issues fast.
How should I use the Azure Networking sheet?
Go top to bottom — easy to hard. Answer before opening each answer, tick what you solved and save misses to Last-Minute Revision.