Job posts that mention containers rarely say whether they mean Docker on a host, Kubernetes in a cluster, or both. DCA, CKA, and OSPI Docker Administrator get compared anyway because all three show up on operator resume lines.
Each exam tests a different layer. This article compares format, cost, validity, salary signals, ROI, and which credential matches which job.
At a glance
| Credential | Format | Primary focus | Typical cost | Validity |
|---|---|---|---|---|
| OSPI Docker Administrator (CTR-OPS-101) | Live lab (SSH) | Docker Engine, Compose, Swarm on Linux | $199 USD | 3 years |
| Docker Certified Associate (DCA) | Proctored multiple choice | Docker knowledge recall | $195 USD | 2 years |
| Certified Kubernetes Administrator (CKA) | Performance-based (kubectl) | Kubernetes cluster administration | $445 USD | 2 years |
CKA price includes two exam attempts and simulator access per the Linux Foundation. Last reviewed June 2026.
Salary and career outcomes
Certifications do not guarantee a raise. They change how recruiters filter resumes and what you can argue in negotiation. Treat the numbers below as market signals from job-listing and survey data, not promises.
| Credential | Typical roles | US compensation signal | What the cert usually buys you |
|---|---|---|---|
| OSPI Docker Administrator | DevOps engineer, platform engineer, backend engineer with container duties | Docker roles cluster around an ~$85k median in published listings; senior DevOps ranges run higher | Live-lab proof for interviews; no large-scale salary survey yet for OSPI specifically |
| Mirantis DCA | DevOps, platform, SRE, container specialist | Third-party aggregates cite roughly $105k-$145k for DevOps roles with DCA versus ~$95k-$130k without | Docker keyword on resume and compliance checklists; smaller premium than CKA in most surveys |
| CNCF CKA | Platform engineer, SRE, Kubernetes administrator, cloud infrastructure engineer | $125k-$160k mid-level; senior SRE often higher. Surveys report an 18-25% premium vs non-certified peers in similar roles | Strongest job-posting signal of the three; hands-on kubectl proof for cluster admin hiring |
Salary figures mix published job ads, self-reported surveys, and training-vendor aggregates. They vary by city, company, and years of experience. Last reviewed June 2026.
Docker skill demand remains broad: roughly 2,000 active US listings mention Docker, mostly mid-level and senior roles per Datamata job-market data. Kubernetes demand is narrower but pays more on average. Comparisons of DCA versus CKA often show roughly twice as many listings mentioning Kubernetes certification and a higher average salary band for CKA-aligned roles.
ROI: exam cost vs. upside
| Credential | Exam cost | Conservative annual upside | Rough payback if upside hits |
|---|---|---|---|
| OSPI CTR-OPS-101 | $199 | $5k-$10k/year (Docker DevOps roles; comparable to DCA band estimates) | About 2-4 weeks of incremental pay at that rate |
| Mirantis DCA | $195 | $5k-$10k/year (low end of third-party DCA estimates) | About 2-5 weeks of incremental pay at that rate |
| CNCF CKA | $445 (two attempts included) | $10k-$20k/year (common survey range for CKA holders) | About 2-4 weeks of incremental pay at that rate |
CKA costs more upfront but includes a retake and simulator access on the Linux Foundation exam page. OSPI and DCA are cheaper tickets with shorter validity windows for DCA (two years) versus OSPI (three years). Factor renewal fees if you plan to keep credentials current across a multi-year career.
Outcomes beyond salary matter too. A live lab pass gives you a concrete story for technical interviews: what broke, what you ran, how long it took. DCA helps when HR software matches acronyms before a human reads your application. CKA helps when the hiring manager needs someone who has already worked in a kubectl terminal under pressure.
The three credentials
OSPI Certified: Docker Administrator
Open Source Proficiency Institute
- Format
- Performance-based live lab (SSH)
- Duration
- 2 hours
- Price
- $199 USD
- Validity
- 3 years
Best for: Operators who run Docker on Linux hosts and need exam day to feel like a shift.
Strengths
- Live Linux tasks on Engine, Compose, networks, volumes, and Swarm
- Same price band as DCA with a longer validity window
- Vendor-neutral Docker ops proof with public verification
Watch outs
- Does not test Kubernetes cluster administration
- Less name recognition than DCA or CKA today
- Requires solid Linux CLI habits under time pressure
Docker Certified Associate (DCA)
Mirantis
- Format
- Proctored multiple choice
- Duration
- 90 minutes (~55 questions)
- Price
- $195 USD
- Validity
- 2 years
Best for: Candidates who need the best-known Docker cert title on a resume or compliance form.
Strengths
- Strongest Docker brand recognition in hiring filters
- Fixed exam fee and predictable registration path
- Broad coverage of Engine, Swarm, networking, and storage
Watch outs
- Multiple choice only; no live troubleshooting lab
- Heavy Swarm weight while many teams moved to Compose or Kubernetes
- Two-year renewal through the same exam style
Certified Kubernetes Administrator (CKA)
CNCF / Linux Foundation
- Format
- Performance-based (kubectl, terminal)
- Duration
- 2 hours (~15-20 tasks)
- Price
- $445 USD
- Validity
- 2 years
Best for: Platform and infrastructure engineers who administer production Kubernetes clusters.
Strengths
- Hands-on kubectl exam, not multiple choice
- Widely recognized standard for Kubernetes operations roles
- Two attempts and simulator sessions included in the exam fee
Watch outs
- Tests Kubernetes, not Docker Engine day-two work on a single host
- Highest cost on this list
- Cluster admin scope is broader than most Docker-only job posts need
Different layers, different exams
Docker and Kubernetes overlap in daily conversation. On exam day they do not overlap much.
OSPI CTR-OPS-101 and DCA both sit in the Docker lane: images, containers, Compose files, networks, and volumes on Linux. CKA sits in the orchestration lane: nodes, pods, services, storage classes, and cluster troubleshooting with kubectl. Passing CKA does not prove you can recover a broken Compose stack on one VM. Passing DCA does not prove you can fix a failing Deployment across three worker nodes.
Many teams use both: Docker (or containerd) on hosts, Kubernetes above it. The cert you need follows the work you are hired to do first.
When each credential wins
Pick OSPI Docker Administrator when
Your role is day-two Docker on Linux: pull images, fix Compose deployments, debug networking, and recover from break-fix scenarios under time pressure. You want a live lab grade without sitting a Kubernetes exam. OSPI also fits if you care about credential validity: three years versus two for DCA and CKA.
Pick DCA when
The posting, vendor checklist, or manager names Docker Certified Associate explicitly. DCA still wins keyword searches even when the daily work looks more like Compose than Swarm. It is also the cheapest proctored Docker credential on this list if you only need the title and accept multiple-choice format.
Pick CKA when
The job centers on Kubernetes cluster operations: scheduling, networking, storage, upgrades, and incident response with kubectl. Platform and SRE roles that mention Kubernetes in the title usually mean CKA territory, not Docker Engine trivia. Budget for $445 USD and prep time on real clusters, not just Docker Desktop.
Common mistakes
Sitting CKA to satisfy a Docker-only job post is the most frequent mismatch. Recruiters may equate containers with Kubernetes, but a team running Compose on two hosts will not care about your etcd backup procedure.
Sitting DCA alone when the interview is a live terminal session is the second mismatch. Multiple-choice recall and SSH troubleshooting are different skills. If the screen involves fixing a running stack, OSPI or CKA style prep fits better than question banks alone.
Study resources by credential
OSPI Docker Administrator (CTR-OPS-101)
- Exam scope: OSPI exam objectives and enrollment
- Exam day logistics: candidate documentation (check-in, SSH, credential validity)
- Official reference: Docker Engine docs, Compose docs, Swarm docs
- Free drills: Play with Docker for short sessions; use a local Linux VM or cloud instance for full break-fix practice
- Related reading: Best Alternative to DCA, Docker cert study guide
Mirantis DCA
- Registration: Mirantis DCA exam page
- Structured prep: Docker Mastery (Udemy), KodeKloud DCA course
- Official training: Mirantis Docker certification training
- Reference: same Docker docs as above; weight Swarm and networking heavily for the blueprint
CNCF CKA
- Registration: CKA exam page (includes Killer.sh simulator sessions)
- Curriculum: Kubernetes Fundamentals (LFS258), Kubernetes Administration (LFS458)
- Popular prep: KodeKloud CKA course
- Exam docs allowed during CKA: kubernetes.io/docs (practice navigating before exam day)
- Lab options: kind, minikube, or a small cloud cluster for kubectl repetition
- Career context: CNCF annual survey for Kubernetes adoption trends
Can you hold more than one?
Yes, and many senior operators do. Aggregated comparisons suggest holding both DCA and CKA can land in a higher band than either alone on paper, though overlap is real and experience still drives compensation (ExamCert comparison). A practical sequence for full-stack container work: OSPI or DCA for Docker fundamentals, then CKA once you administer clusters weekly. DCA plus OSPI is less common but reasonable when you need the Mirantis keyword and a live lab story for interviews.
For deeper Docker-only comparisons, see Best Alternative to the Docker Certified Associate and The 5 Best Docker Certifications of 2026.
How to choose this week
Read the last three job posts you saved. Highlight whether they mention Kubernetes, Docker, or both. Match that list to one exam before you buy a voucher. Check published pay on those postings if compensation is listed. If the answer is Docker on Linux hosts, start with the CTR-OPS-101 objectives and a local Linux VM. If the answer is cluster admin, build a small kubeadm, kind, or minikube lab and work through the Kubernetes docs before you schedule CKA.
One credential that matches your actual stack beats three badges that do not survive the first technical screen.