#aws-networking
How traffic actually moves through an AWS account — VPC routing, MTU, DNS limits, NAT paths, and the per-gigabyte charges attached to each of them.
4 articles tagged #aws-networking, newest first.
EC2 MTU: 1500 vs 9001, and Why Jumbo Frames Break at the VPC Edge
EC2 instances default to a 9001-byte MTU inside the VPC and 1500 bytes to the internet. Where the boundary sits, and why transfers hang while pings succeed.
Why AWS Reserves 5 IP Addresses in Every Subnet (and What Each One Does)
AWS takes five addresses out of every VPC subnet: network, router, DNS resolver, one in reserve, and broadcast. What each is for, and how it changes sizing.
NAT Gateway vs NAT Instance vs VPC Endpoint: Which One, and What It Costs
Three ways to give private subnets outbound access, with very different bills. Where each one wins, and why an S3 gateway endpoint is the cheapest fix.
The VPC DNS Limit: 1,024 Packets per Second per ENI
The VPC resolver caps every network interface at 1,024 DNS packets per second. It is not adjustable, has no CloudWatch metric, and looks like random SERVFAIL.