Hands-on practice is the fastest way to make ANS-C01 routing and troubleshooting scenarios understandable. Use a cost-controlled sandbox or AWS training labs and build one reference architecture that evolves from a single VPC into multi-account, hybrid, global, and secured networking. The current ANS-C01 exam retires December 31, 2026, so practical work should be tightly aligned with the four live domains.
Lab one: build a VPC with explicit routing
Create public and private subnets across at least two Availability Zones, add route tables, internet gateway and controlled outbound access. Use security groups and NACLs deliberately rather than accepting defaults.
Document each route and why it exists before adding more services.
Lab two: compare NAT, endpoints, and direct internet paths
Send one private workload outbound through NAT and access an AWS service through a VPC endpoint where supported. Observe the route and source-address behavior.
A NAT Gateway lab is useful because it makes centralized outbound translation distinct from private service access.
Lab three: connect two VPCs, then scale the topology
Start with VPC peering and verify routes/security. Add a third VPC and observe why peering does not create automatic transitive routing.
Then redesign conceptually or practically with Transit Gateway and separate route tables for segmentation.
Lab four: create public and private DNS behavior
Build Route 53 public/private hosted zones using harmless test names. Configure health checks or routing policies where practical and inspect resolution from inside and outside the VPC.
Then model Resolver inbound/outbound endpoints for hybrid DNS.
Lab five: compare edge and load-balancing patterns
Put a small web app behind an ALB or NLB and inspect health behavior. Add CloudFront or Global Accelerator conceptually or in a low-cost lab.
Use ELB, CloudFront, and Global Accelerator as three different traffic-distribution layers rather than interchangeable services.
Lab six: build a hybrid routing tabletop
If Direct Connect is not practical, use a detailed diagram with Site-to-Site VPN, BGP prefixes, customer gateway, Transit Gateway or virtual private gateway, primary/backup paths and route propagation.
Introduce a missing advertisement or asymmetric return route and troubleshoot from the route tables.
Lab seven: automate a repeatable network
Deploy a small VPC and route structure through infrastructure as code. Change one parameter, review the diff and redeploy. The goal is proving repeatability and reducing console drift.
Keep blast radius small and validate routes/security after every automation change.
Lab eight: generate and analyze network telemetry
Enable VPC Flow Logs on a test scope, inspect load-balancer or VPN metrics, and create one controlled blocked connection. Identify source, destination, action and the enforcement point.
Operations practice should answer “what happened?” before “what should I change?”
Lab nine: add centralized security
Create or diagram centralized inspection with AWS Network Firewall or a security VPC pattern. Compare distributed security groups and NACLs with centralized inspection and application-layer protection through WAF/Shield where appropriate.
Then verify that return routes still pass through the intended inspection path.
Lab ten: run a blind end-to-end incident
Introduce one harmless failure—DNS resolution, route propagation, security rule, load-balancer health or hybrid prefix—and diagnose from evidence without being told the domain. Record hypothesis, evidence, root cause, fix and validation.
Add an IPv6 branch to the first VPC lab. Assign dual-stack subnets where supported, inspect IPv6 routes and compare internet egress behavior with IPv4. The exam expects networking fundamentals across both protocol families, and practical dual-stack exposure prevents IPv6 from remaining a memorized appendix.
Add a route-selection worksheet to every lab. For a source and destination, list the subnet route table, longest-prefix match, propagated/static routes, gateway or Transit Gateway route, and return path. This single habit makes complex AWS routing scenarios much easier to debug.
Add a Transit Gateway segmentation exercise with at least two route tables. Permit application VPCs to reach shared services but block direct connectivity between two isolated environments. Confirm the result from both directions so asymmetric assumptions do not hide a leak.
Add a Route 53 Resolver lab or diagram with inbound and outbound endpoints. Let on-premises clients resolve a private AWS zone and AWS workloads resolve one internal on-premises zone. Then intentionally create a bad forwarding rule and trace the failure.
Add a Route 53 routing-policy exercise using latency, failover, weighted, geolocation, or multivalue behavior in a harmless test domain. Observe that DNS answers influence endpoint selection but do not guarantee application success if the selected target is unhealthy beyond the DNS health logic.
Add a Network Load Balancer versus Application Load Balancer comparison with the same simple service. Record protocol, target type, TLS handling, source IP, health check, and Layer 7 routing differences. Service selection becomes easier when behavior is observed rather than summarized.
Add an AWS Global Accelerator architecture diagram even if you skip deployment cost. Show anycast IPs, edge locations, endpoint groups, regional endpoints, health, and traffic dials. Compare its path with Route 53 DNS selection and CloudFront caching.
Add a hybrid BGP tabletop with two routes to the same prefix. Change route specificity or customer-side policy and predict which path is selected. Hybrid networking is much easier when route preference is calculated explicitly rather than inferred from “primary” labels.
Add a Direct Connect resilience design with two physical locations or provider paths on paper. Identify single points of failure such as one customer router, one colocation facility, or one Direct Connect location. Then decide where VPN backup fits.
Add centralized DNS governance across accounts. Use Resource Access Manager or documented ownership to share resolver rules where appropriate and decide which team owns private zones. DNS changes can affect many applications, so ownership and change control matter.
Add centralized inspection routing. Place Network Firewall or a virtual appliance conceptually between spokes and egress, then confirm forward and return traffic traverse the same stateful path. One missing return route can make the firewall appear “broken” when the topology is asymmetric.
Add WAF and Shield at the public application edge. Use benign requests and managed rules where a training environment permits it. Record that WAF evaluates web-layer requests while Shield addresses DDoS protection and VPC controls handle different network layers.
Add a flow-log analysis exercise. Create a security-group deny or NACL deny and compare the resulting evidence with a missing route or unhealthy application target. Flow logs can show traffic acceptance/rejection but cannot prove that the application returned a correct response.
Add a CloudTrail change-attribution exercise for a routing or security modification. Identify which principal changed the route table or security group and when. During real incidents, knowing who changed configuration can separate deliberate deployment from unexpected behavior.
Add a cost worksheet after every network path. Note NAT processing, Transit Gateway data processing, inter-AZ or inter-Region transfer, Direct Connect, internet egress, and edge-service cost categories conceptually. ANS-C01 expects design decisions that can include cost, not only reachability.
Add a multi-account deployment exercise with infrastructure as code. Parameterize account/Region-specific CIDRs and validate that shared networking resources are referenced correctly. Keep privileged network changes behind review because a wrong template can disconnect many workloads simultaneously.
Add a disaster-recovery networking rehearsal. Pre-create routes, security groups, resolver rules and global failover behavior in the secondary Region, then simulate endpoint failure. A DR network that has never carried traffic can hide route or DNS defects until the worst possible moment.
Finish by documenting each lab with topology, intended traffic flow, route decisions, security enforcement, telemetry, expected cost, failure introduced, and recovery. That record becomes a compact study resource and trains the same systems thinking the specialty exam requires.
Add a security-group versus NACL experiment. Deny or allow the same test flow at each layer in a disposable VPC and observe stateful versus stateless behavior. This is more useful than memorizing the definitions because return traffic and rule ordering become visible.
Add an interface-endpoint DNS exercise. Create a supported interface endpoint, inspect the endpoint ENIs and private DNS behavior, then disable or alter private DNS and compare resolution. This demonstrates why a private endpoint can exist while clients still use a public endpoint.
Add a Site-to-Site VPN lab using two AWS VPCs with a virtual router appliance or a vendor lab if on-premises equipment is unavailable. Practice both tunnel state and actual routed traffic. A “UP” tunnel is not proof that the desired prefixes are exchanged or allowed.
Add a Transit Gateway flow-log or route-table evidence exercise. Generate one allowed path and one intentionally missing route, then compare the evidence. This helps distinguish transit routing failure from workload security-group denial.
Add a Route 53 Resolver rule-sharing exercise on paper or across test accounts. Decide which account owns the rule, which VPCs can associate it, and how on-premises DNS reaches the inbound endpoint. Cross-account DNS is as much governance as configuration.
Add a TLS termination map for one application. Mark where encryption terminates at CloudFront, ALB/NLB, or backend, how certificates are managed, and whether re-encryption occurs. Security scenarios become easier when confidentiality is traced hop by hop.
Add a DDoS/WAF response tabletop. Simulate a volumetric event and a malicious HTTP request separately. Decide which service protects against which behavior and which logs/metrics show the event. This reinforces that “internet attack” is not one network layer.
Add a multi-Region Route 53 or Global Accelerator failover test. Fail the primary endpoint, observe health-based traffic movement, and measure how quickly a client sees the change. Then compare DNS caching behavior with anycast-based accelerator routing.
Add one service-quota preflight checklist before a scale-out lab. Check VPC, Transit Gateway, NAT, load-balancer, resolver, route, and VPN/Direct Connect related limits relevant to the design. Quotas are part of architecture because a theoretically elegant design can fail at scale if resource limits are ignored.
Add one post-change verification checklist to every lab: DNS result, route, security, target health, telemetry, application test, and rollback. This builds professional change discipline and prevents the common habit of declaring success when the control-plane API returns “complete.”
For the final practical exercise, reproduce the architecture from code in a fresh sandbox or account where possible. Hidden manual prerequisites—shared routes, resolver associations, policy exceptions, or security rules—will become obvious when the environment has to rebuild from source.
An ANS-C01 hands-on plan should end with this kind of cross-domain troubleshooting because the specialty exam is designed for experienced networking practitioners, not service-definition recall.