Gateway VPC endpoints are a powerful networking feature in AWS that enable private connectivity between your Virtual Private Cloud (VPC) and supported AWS services, specifically Amazon S3 and DynamoDB. These endpoints allow traffic to flow between your VPC and the target service through the AWS net…Gateway VPC endpoints are a powerful networking feature in AWS that enable private connectivity between your Virtual Private Cloud (VPC) and supported AWS services, specifically Amazon S3 and DynamoDB. These endpoints allow traffic to flow between your VPC and the target service through the AWS network backbone, eliminating the need for an internet gateway, NAT device, or VPN connection.
When you create a Gateway VPC endpoint, AWS provisions a gateway target in your VPC route tables. You specify which route tables should include routes to the endpoint, and AWS automatically adds a prefix list entry pointing to the endpoint. This means EC2 instances in subnets associated with those route tables can access S3 or DynamoDB using their public endpoints, but the traffic remains within the AWS network.
Key characteristics of Gateway VPC endpoints include: they are horizontally scaled, redundant, and highly available VPC components. They do not impose bandwidth constraints and incur no additional charges for their use. You can attach endpoint policies to control which principals can access the service and which resources they can access.
For the SysOps Administrator exam, understanding these important aspects is crucial: Gateway endpoints only support IPv4 traffic, they cannot be extended outside your VPC, and they cannot be used across VPC peering, VPN connections, or AWS Transit Gateway. You must also understand how to configure route tables properly and how to implement endpoint policies for security.
Monitoring Gateway VPC endpoints involves using VPC Flow Logs to capture traffic information and CloudTrail to audit API calls made through the endpoint. When troubleshooting connectivity issues, administrators should verify route table configurations, security group rules, network ACLs, and endpoint policies to ensure proper access to S3 or DynamoDB resources through the endpoint.
Gateway VPC Endpoints: Complete Guide for AWS SysOps Administrator Associate
What are Gateway VPC Endpoints?
Gateway VPC Endpoints are a type of VPC endpoint that enables private connectivity between your VPC and supported AWS services. They are specifically designed for Amazon S3 and DynamoDB only. These endpoints appear as route table entries (prefix lists) rather than elastic network interfaces.
Why are Gateway VPC Endpoints Important?
• Cost Savings: Gateway endpoints are free to use - there are no hourly charges or data processing fees • Security: Traffic remains within the AWS network and never traverses the public internet • Performance: Provides reliable, low-latency connectivity to S3 and DynamoDB • Compliance: Helps meet regulatory requirements by keeping data within private networks • Reduced NAT Gateway Costs: Prevents S3/DynamoDB traffic from going through NAT gateways, saving significant money
How Gateway VPC Endpoints Work
1. Creation: You create a gateway endpoint and associate it with one or more route tables in your VPC
2. Route Table Entry: AWS adds a route to the specified route tables with the destination as a prefix list (pl-xxxxxxxx) pointing to the endpoint
3. Traffic Flow: When instances in subnets associated with those route tables access S3 or DynamoDB, traffic is routed through the gateway endpoint
4. DNS Resolution: Standard DNS names for S3 and DynamoDB resolve to public IP addresses, but traffic is routed through the endpoint based on route table entries
Key Characteristics
• Gateway endpoints are regional - they work only within the same region • They are horizontally scaled, redundant, and highly available • You can have multiple gateway endpoints in a single VPC • Endpoint policies can restrict which resources can be accessed • They do NOT support cross-region access • They do NOT support on-premises access through VPN or Direct Connect
Gateway vs Interface Endpoints
Gateway Endpoints: • Support S3 and DynamoDB only • Free to use • Use route table entries • Cannot be extended to on-premises
Interface Endpoints: • Support many AWS services • Have hourly and data processing charges • Use elastic network interfaces with private IPs • Can be extended to on-premises via VPN/Direct Connect
Endpoint Policies
Gateway endpoints support endpoint policies - IAM resource policies that control access to the service from the endpoint. You can: • Restrict access to specific S3 buckets • Limit actions that can be performed • Control which principals can use the endpoint
Exam Tips: Answering Questions on Gateway VPC Endpoints
• Remember the two services: Gateway endpoints support only S3 and DynamoDB - this is frequently tested
• Cost optimization scenarios: When asked about reducing data transfer costs for S3 or DynamoDB access, gateway endpoints are the answer since they are free
• Route table association: Questions may ask about why traffic isn't flowing through the endpoint - check that the correct route tables are associated
• On-premises connectivity: If a question involves accessing S3/DynamoDB from on-premises through VPN or Direct Connect, an Interface Endpoint is required, not a gateway endpoint
• Security requirements: When scenarios mention keeping traffic private or off the internet, gateway endpoints for S3/DynamoDB are appropriate
• Regional scope: Gateway endpoints only work within the same region - cross-region S3 access still uses the internet or other mechanisms
• Prefix lists: Questions about security groups referencing S3 or DynamoDB endpoints use prefix lists (pl-xxxxxxxx)
• High availability: Gateway endpoints are managed by AWS and are inherently highly available - no need for redundancy planning
• Troubleshooting: If instances cannot reach S3/DynamoDB through a gateway endpoint, verify: route table associations, endpoint policy permissions, and bucket policies