Easy everything in DevOps & Cloud, page 4
Purpose and setup of a Dead-Letter Queue
A DLQ captures messages that repeatedly fail so they neither block the queue nor get lost; configure a redrive policy with a max receive count and alarm on it.
Serverless cold starts and how to mitigate them
A cold start is the latency to provision and initialize a fresh environment; mitigate with provisioned concurrency, smaller packages, and lighter runtimes.
Kubernetes Deployment versus Pod
A Pod is the smallest disposable unit, a Deployment maintains a desired replica count, self-heals, and rolls out updates.
Writing a Dockerfile for a web app
FROM a base, set WORKDIR, install dependencies before app code for cache reuse, EXPOSE the port, CMD the start command.
Deploying to Heroku via Git
Push to the remote, a buildpack detects the language, builds a slug, and runs the Procfile process.
Why not store uploads on local PaaS disk?
PaaS instances are ephemeral and unshared, so local files vanish on restart and are invisible to peers; store uploads in object storage.
The cloud shared responsibility model
The provider secures the cloud (hardware, OS, runtime), you secure what runs in it (code, data, config, access).
How does caching reduce database load?
Cache-aside reads, RAM-speed lookups, TTL plus invalidation.
Read replicas in managed relational databases
A read replica is an async copy of the primary that serves read-only queries, offloading the primary and scaling read-heavy workloads; expect replication lag.
Choosing relational vs NoSQL managed databases
Choose relational for complex relationships, joins, flexible queries, and strong transactions; choose NoSQL for known access patterns needing massive horizontal scale.
Security Groups vs NACLs
A security group is stateful and attached to instances or NICs; a NACL is stateless and applied at the subnet.
IAM Role vs IAM User
A user is a fixed identity with long-lived credentials for a person; a role is assumable with temporary credentials for workloads or cross-account access.
How cloud DNS resolves a URL to an IP
Recursive resolver queries root, then TLD, then your authoritative cloud DNS zone; the matching record returns an IP, cached per TTL.
Layer 4 vs Layer 7 load balancers
L4 routes on IP and TCP/UDP ports fast and protocol-blind; L7 inspects HTTP for host, path, and headers.
Public and private subnet VPC design
Web server in a public subnet routed to an internet gateway, database in a private subnet with no inbound from the internet, NAT for outbound.
Serving user images securely from object storage
Store images in a private bucket, serve via a CDN with origin access control, use signed URLs for private content.
Object vs block vs file storage
Object stores flat keyed blobs over HTTP, block gives raw volumes for one VM, file offers a shared hierarchical mount.
What a machine image is and why it matters
An image is a frozen template of OS, software, and config; it makes launches identical and fast.
Launching a virtual machine in the cloud
Pick image, instance type, network placement and security, attached storage, and access keys.
CapEx vs OpEx in cloud migration
CapEx is large upfront asset spend, OpEx is ongoing pay-as-you-go cost; cloud shifts spending from CapEx to OpEx, trading ownership for flexibility.
We are hiring for this. Every open role lists the topics its interview covers, so you can prepare for the real thing rather than guessing.
See open roles