Aws on IT Comparison

NAT Gateway vs Internet Gateway: Who Gets to Talk to the Internet

Mon, 03 Aug 2026 06:27:51 +0900

Overview

Both connect a VPC to the internet, but they serve opposite purposes: an Internet Gateway lets public-facing resources send and receive traffic directly, while a NAT Gateway lets private resources reach out without ever being reachable from outside. Picking the wrong one either exposes resources you meant to keep private or silently blocks the outbound access your servers need.

Comparison Diagram

Comparison Table

Aspect	Internet Gateway	NAT Gateway
Primary purpose	Enables communication between a VPC and the internet in both directions	Enables outbound-only internet access for resources without public IPs
Traffic direction	Bidirectional — accepts inbound connections and sends outbound	Outbound only — inbound traffic allowed only as replies to established connections
Placement	Attaches directly to the VPC as a whole	Deployed inside a specific public subnet
IP address handling	1:1 NAT between a private IP and an Elastic/public IP	Many-to-one PAT — many private IPs share the gateway’s public IP
Which resources use it	Instances with a public/Elastic IP routed via a public subnet route table	Instances with only private IPs routed via a private subnet route table
Scaling and availability	Managed, horizontally scaled, highly available with no bandwidth cap	Bandwidth-bounded per gateway; needs one per AZ for high availability
Cost model	No hourly charge and no data processing fee	Hourly charge plus per-GB data processing fee
Failure impact	Loss cuts off all direct internet reachability for the public subnet	Loss cuts off outbound internet access for the private subnet only

Key Differences

Internet Gateway provides bidirectional access; NAT Gateway only permits outbound connections.
Internet Gateway attaches to the whole VPC; NAT Gateway lives inside a specific subnet.
Internet Gateway does 1:1 Elastic IP mapping; NAT Gateway does many-to-one PAT.
NAT Gateway bills per GB processed; Internet Gateway is free.

When to Use Each

Internet Gateway

Availability Zone vs Region: Scope of Cloud Infrastructure Isolation

Mon, 03 Aug 2026 06:26:19 +0900

Overview

An Availability Zone is one or more physically isolated data centers with independent power, cooling, and networking, while a Region is a broader geographic area made up of multiple such zones connected by low-latency links. The distinction matters because it determines what kind of failure your architecture survives — a single data-center outage versus a region-wide disaster — and what compliance jurisdiction your data falls under.

Comparison Diagram

Comparison Table

Aspect	Availability Zone	Region
Definition	One or more discrete data centers with independent power, cooling, and networking	A geographic area containing multiple availability zones
Physical composition	Typically 1+ physical data center buildings	Multiple AZs (often 3 or more) plus regional network backbone
Inter-node latency	Sub-millisecond to a few milliseconds over private links between AZs	Tens to hundreds of milliseconds over public/backbone links between regions
Failure isolation	Isolates against power, cooling, or single data-center failures	Isolates against natural disasters or systemic events affecting an entire geography
Redundancy pattern used for	High availability within one geographic area	Disaster recovery and global latency reduction across geographies
Data residency & compliance	No effect — all AZs in a region share the same jurisdiction	Determines the legal jurisdiction and data residency boundary
Data transfer cost	Low intra-region rate for traffic between AZs	Higher inter-region or egress rate for traffic between regions

Key Differences

An Availability Zone is one or more data centers, while a Region is the geographic area that groups several AZs together
Inter-AZ traffic uses low-latency private links; inter-region traffic crosses public backbone networks with far higher latency
Multi-AZ deployments protect against data-center outages; multi-region deployments protect against regional disasters
Region choice fixes your data residency and compliance jurisdiction — AZ choice does not
Cross-AZ transfer is cheap; cross-region transfer incurs higher egress costs

When to Use Each

Availability Zone

Spot Instances vs On-Demand Instances: When Cheap Compute Comes With Strings Attached

Mon, 03 Aug 2026 06:25:19 +0900

Overview

Both are ways to rent compute capacity from a cloud provider, but they trade cost against reliability in opposite directions. Spot Instances tap into unused capacity at steep discounts but can be reclaimed with almost no notice, while On-Demand Instances cost more per hour in exchange for a guaranteed, uninterrupted slot.

Comparison Diagram

Comparison Table

Aspect	Spot Instances	On-Demand Instances
Request & provisioning	Fulfilled only if provider has spare capacity at your bid price	Fulfilled immediately from reserved capacity pools
Capacity guarantee	None — provider can reclaim the instance at any time	Guaranteed for as long as you keep paying
Pricing model	Variable, set by real-time supply and demand for spare capacity	Fixed hourly rate published by the provider
Interruption behavior	Reclaimed with a short warning (e.g. ~2 minutes on AWS)	Never interrupted by the provider; you control shutdown
Cost predictability	Fluctuates; can spike or be revoked when demand rises	Stable and predictable, easy to forecast in a budget
Ideal workloads	Fault-tolerant, stateless, or checkpointable batch jobs	Stateful, latency-sensitive, or continuously running services
Termination control	Provider-initiated; your app must handle abrupt shutdown	User-initiated; you decide exactly when it stops

Key Differences

Spot pricing floats with market demand and can be up to 90% cheaper than On-Demand rates
Spot capacity is reclaimable at any time, typically with only a short warning window
On-Demand gives a firm capacity guarantee that Spot never promises
Workloads on Spot need to tolerate sudden termination or design for checkpointing
On-Demand cost is fixed and predictable, while Spot cost is variable and market-driven

When to Use Each

Spot Instances