IT Operations & Cybersecurity Encyclopedia
AWS VPC architecture review guide
An AWS VPC architecture review helps confirm that cloud networks are segmented, routed, logged, resilient, and governed correctly. A useful review examines VPCs, subnets, route tables, internet and NAT gateways, security groups, network ACLs, endpoints, peering, transit paths, DNS, flow logs, and ownership.
VPC designSubnet routingSecurity groupsVPC endpointsFlow logs
Why it matters
Make cloud network paths intentional, documented, and reviewable
AWS VPC design affects application security, internet exposure, east-west traffic, private connectivity, logging, resilience, cost, and troubleshooting. Small routing or security group mistakes can expose workloads or break critical dependencies.
A mature review maps each VPC to business purpose, identifies public and private subnets, validates route tables, checks security groups and network ACLs, reviews connectivity patterns, and confirms monitoring evidence.
This guide helps IT, cloud, and security teams review AWS VPC architecture. It does not replace a professional cloud architecture assessment, penetration test, or compliance audit.
Practical rule: Every VPC should have a business owner, environment label, subnet purpose, route table review, security boundary, logging status, and documented connectivity to other networks.
Review scope
AWS VPC architecture review domains
VPC inventory
Document accounts, regions, CIDR ranges, owners, environments, tags, and business purpose.
Subnet and route design
Review public/private subnet placement, route tables, internet access, NAT gateways, and AZ coverage.
Network security controls
Inspect security groups, NACLs, admin exposure, egress paths, and exception handling.
Private connectivity
Validate VPC endpoints, endpoint policies, peering, Transit Gateway, VPN, Direct Connect, and DNS.
Monitoring and logs
Confirm VPC Flow Logs, rejected traffic review, route changes, SIEM delivery, alerts, and retention.
Resilience and operations
Check multi-AZ design, failure paths, change control, cost implications, and operational runbooks.
Review matrix
AWS VPC architecture review matrix
| Area | What to verify | Questions to answer | Evidence |
|---|---|---|---|
| VPC inventory | Account, region, VPC ID, CIDR, environment, owner, tags, and application mapping. | What VPCs exist and what do they support? | VPC export, tag report, architecture diagram, and owner approval. |
| Subnet and routing | Subnet purpose, route tables, public routes, NAT, gateways, AZ placement, and route associations. | Are network paths intentional and documented? | Subnet map, route table export, gateway list, and routing review notes. |
| Security groups and NACLs | Ingress, egress, admin access, broad rules, service ports, ephemeral rules, and exception owners. | What traffic is allowed at workload and subnet boundaries? | Security group export, NACL export, risky rule list, and remediation tickets. |
| Private access and endpoints | VPC endpoints, endpoint policies, DNS, service access, peering, Transit Gateway, VPN, and Direct Connect. | Can workloads use private paths instead of unnecessary internet routes? | Endpoint list, policy export, DNS settings, connectivity map, and test result. |
| Logging and visibility | VPC Flow Logs, delivery destination, rejected traffic, route changes, alerts, retention, and SIEM integration. | Can network activity be investigated? | Flow log configuration, sample event, alert rule, retention setting, and review notes. |
| Resilience and operations | AZ design, NAT gateway placement, route failover, dependency mapping, change control, and rollback. | Can the VPC survive expected failures and changes? | AZ map, failover notes, change ticket, rollback plan, and validation evidence. |
Step-by-step review
AWS VPC architecture review runbook
1
Inventory VPCs and owners
List AWS accounts, regions, VPC IDs, CIDRs, tags, application owners, environments, and business purpose.
2
Map subnets and routes
Review subnet purpose, route table associations, public paths, NAT, internet gateways, Transit Gateway, VPN, and peering.
3
Review security boundaries
Inspect security groups, NACLs, broad ingress, egress, admin ports, internet exposure, and exception records.
4
Validate private access
Check VPC endpoints, endpoint policies, DNS, service dependencies, and whether private paths are used where appropriate.
5
Check logging and monitoring
Confirm VPC Flow Logs, CloudWatch or SIEM delivery, alerting, retention, rejected traffic review, and route-change visibility.
6
Assess resilience
Review multi-AZ placement, NAT gateway design, route failover, dependency maps, and disaster recovery assumptions.
7
Document remediation
Prioritize routing, exposure, logging, segmentation, resilience, ownership, and cost improvements with validation steps.
Common risks
Common AWS VPC architecture review risks
Unclear subnet purpose
Subnets without purpose labels make routing, security boundaries, and troubleshooting harder to govern.
Broad security group rules
Open ingress or egress rules can expose workloads beyond business need.
Missing flow logs
Without flow logs, rejected traffic, investigation, and network evidence are difficult to review.
Overused public routes
Workloads may reach AWS services over internet paths when private endpoints would reduce exposure.
Unreviewed peering or transit
VPC peering, Transit Gateway, VPN, and Direct Connect paths can create unexpected lateral movement.
Single-AZ dependency
NAT, routing, or workload designs can create availability gaps if AZ failure assumptions are not reviewed.
Related support
Where IT Perfection can help
IT Perfection can help document AWS VPC design, review routing and segmentation, validate logging, and coordinate remediation with cloud operations teams.
OC Security Audit can help assess AWS network exposure, segmentation, logging evidence, and cloud security readiness.
Created by Ali Hassani, CISO
Professional AWS VPC architecture review support
Ali Hassani brings 25+ years of hands-on experience across IT operations, cybersecurity, Microsoft infrastructure, network security, compliance readiness, cloud services, healthcare IT, MSP services, and business technology leadership.
This guide is for initial education and planning. It does not replace a professional cybersecurity audit, compliance assessment, penetration test, legal review, vendor engineering review, or Microsoft professional services engagement.
AWS VPC review connects routing, segmentation, logging, and resilience
A strong VPC review shows what networks exist, what they connect to, what traffic is allowed, what is logged, who owns each decision, and what needs remediation.
FAQ
AWS VPC architecture review FAQ
What should an AWS VPC review include?
Review VPC inventory, CIDRs, subnets, route tables, gateways, security groups, NACLs, endpoints, connectivity, flow logs, resilience, and owner evidence.
Why are VPC Flow Logs important?
Flow Logs provide visibility into accepted and rejected traffic, helping with troubleshooting, security investigations, and audit evidence.
Should every workload be in a public subnet?
No. Public subnets should be limited to resources that need direct internet exposure. Many workloads should use private subnets with controlled access paths.
How often should VPC architecture be reviewed?
Review VPC architecture at least annually and after major cloud projects, new connectivity, security incidents, mergers, or application migrations.
