TL;DR Question 1, migrate web, batch and legacy apps with scalability and security: legacy and web tiers on EC2 in an Auto Scaling group across multiple Availability Zones, network ACLs plus security groups for defence in layers, and AWS Batch for the batch jobs, because it provisions and releases the compute per job. …

TL;DR The symptom: pods stuck in ContainerCreating, a managed node group failing with InsufficientFreeAddresses, or a cluster update refusing because a subnet has fewer than 6 free addresses. The cause is the same: the subnet was sized for nodes and the Amazon VPC CNI consumes addresses per pod and per ENI. The …

TL;DR A /24 is 256 addresses, 254 hosts in a textbook, and 251 on AWS and Azure or 252 on Google Cloud. Every cloud reserves addresses in every subnet: AWS and Azure the first four and the last (5), Google Cloud the first two and the last two (4). Subtract that number, not 2, from the block size. The table you came …

TL;DR Overlap means one of three things: the ranges are identical (10.0.0.0/16 and 10.0.0.0/16), one contains the other (10.0.0.0/16 contains 10.0.128.0/17), or they are both inside a bigger block you treat as one (10.1.0.0/16 and 10.2.0.0/16 do not overlap; 10.0.0.0/15 contains both 10.0.0.0/16 and 10.1.0.0/16). What …

TL;DR Five tools, one network: 10.0.0.0/16, public and private tiers, several Availability Zones, tested in my browser on 2026-10-19. All five run client-side and all five subtract AWS's five reserved addresses (251 usable per /24). Visual Subnet Calculator is the best tool for exploring an address space: split and …

Part-13 connected VPCs with a Transit Gateway: one hub per region, route tables you write yourself, and peering between regions you also write yourself. This Part-25 is what AWS built on top of that idea: AWS Cloud WAN, where you describe the network you want in one policy document (which regions, which segments, who …

Part-22 kept traffic inside AWS with PrivateLink. This Part-23 is about the opposite direction: users on the public internet, anywhere in the world, reaching an application that runs in more than one region - and reaching the closest healthy copy through one fixed pair of IP addresses. I build it the way I did in the …

Every time I record a VPC video the same question comes back in the comments: "how did you decide on 10.0.1.0/24 for the public subnet and 10.0.2.0/24 for the private one?" The honest answer for a demo is "it was easy to type". The honest answer for a real environment is a lot longer, and I never …

Every EC2 instance we have launched in this series had a disk, and we never looked at it. That disk is an Amazon EBS volume, and in this Part-20 we are going to give it the attention it deserves - because storage is where the two expensive mistakes live: picking the wrong volume type (slow or overpriced) and losing …

Everything we built so far answers on an ugly name - jhooq-web-alb-1234567890.eu-central-1.elb.amazonaws.com. Users need www.jhooq.com, and that is DNS. Amazon Route 53 is the AWS DNS service - a domain registrar, an authoritative DNS server with a 100% availability SLA, health checks, and the routing policies that …