What 1V0-21.20 actually tests

The 1V0-21.20 Associate VMware Data Center Virtualization exam is an entry-level vSphere certification, but do not mistake “associate” for trivial. It checks whether you understand how a VMware virtualized data center is put together, how the core components interact, and what common platform features do.

This exam is best suited to you if you are:

New to VMware but already comfortable with basic server, storage, and networking ideas
Working in IT operations, support, help desk, junior sysadmin, or infrastructure roles
Moving from general virtualization awareness into hands-on vSphere knowledge

Expect the exam to focus on VMware vSphere concepts rather than deep design or advanced troubleshooting. You need to know the purpose, function, and basic administration flow of:

ESXi
vCenter Server
Virtual machines and templates
Clusters and resource management
vSphere networking
vSphere storage
Availability and mobility features such as vMotion, Storage vMotion, HA, and DRS

You should also expect scenario-style questions. Not heavy simulations, but prompts that ask what component fits a requirement, what feature solves a problem, or what prerequisite must exist before an operation can succeed.

Because this is the 2020 associate DCV exam, your study should stay centered on vSphere fundamentals, not older VCP-level blueprint sprawl. That means less obsession with obscure command syntax and more emphasis on understanding platform behavior.

With 97 practice questions available on Truekia, you have enough volume to identify weak areas, but only if you pair those questions with actual reading and lab repetition. Memorizing answers alone is not enough for this exam.

The platform core: ESXi, vCenter, and the anatomy of a vSphere environment

Start here. If your understanding of the core architecture is weak, everything else becomes memorization.

Know the role of each component

You need to clearly separate what happens on ESXi versus what is managed centrally through vCenter Server.

ESXi is the hypervisor installed on physical hosts.
vCenter Server provides centralized management for hosts, clusters, VMs, permissions, alarms, templates, and advanced features.
Many enterprise features require vCenter even though the VM can technically run on a standalone ESXi host.

Typical exam checks in this area:

Which functions require vCenter Server?
What is the difference between managing one host directly and managing hosts through vCenter?
What objects exist in the inventory hierarchy?

Understand the inventory hierarchy

You should know how VMware organizes objects:

Datacenter
Cluster
Host
Virtual machine
Resource pool
Datastore
Network / distributed switch objects
Folders

Be able to explain why a cluster matters. It is not just a container. It is the boundary that enables features like HA and DRS across member hosts.

Be comfortable with VM fundamentals

You will likely see questions on the parts of a virtual machine and what they map to in the physical world.

Study these specifically:

vCPU and CPU scheduling basics
Memory allocation, overhead, and reservation/limit/share concepts at a high level
Virtual disks and datastore placement
VM hardware version
VMware Tools and why they matter
Guest OS compatibility
Snapshots: purpose, limits, and why they are not backups
Templates and cloning

A common weak point: people know snapshots exist but cannot explain the operational risk. You should know that snapshots are useful short-term but can hurt performance and datastore consumption if left in place.

Administrative access and client tools

Know the management interfaces:

vSphere Client for browser-based management
Host Client for direct ESXi host management
Basic awareness of VMware Host Client versus centralized vCenter workflows

You do not need to become a PowerCLI expert for this exam, but basic awareness of VMware automation tooling is helpful context.

Licensing and editions

At associate level, you should understand that VMware features depend on licensing. You do not need to memorize every edition matrix, but you should know that:

Some features are only available when managed through vCenter
Enterprise features can depend on edition/licensing level
Evaluation mode exists and is often used in labs

What to lab in this domain

If you have access to a home or nested lab, do these tasks until they feel boring:

Deploy or access an ESXi host
Log into the Host Client
Add a host to vCenter Server
Create a VM
Install VMware Tools
Take and remove a snapshot
Clone a VM into another VM or template
Create folders and place objects correctly in inventory

If you can explain why an admin would use each object and feature, you are studying the right way.

Compute and availability behavior: clusters, resource controls, vMotion, HA, and DRS

This is one of the most important scoring areas because it covers the features people associate most strongly with vSphere.

Clusters are more than grouping

A cluster aggregates host resources and enables policy-driven behavior. You should understand the purpose of:

vSphere HA
vSphere DRS
vMotion
Enhanced vMotion Compatibility (EVC) at a conceptual level

vMotion and Storage vMotion

You need to know the difference cold.

vMotion moves a running VM from one host to another with no downtime, assuming prerequisites are met.
Storage vMotion moves VM files between datastores while the VM remains powered on.
A VM can also be migrated across both compute and storage depending on setup and licensing.

Know the common prerequisites and dependencies at a high level:

Shared or accessible storage when required
Proper networking for VMkernel migration traffic
CPU compatibility considerations
vCenter involvement for managed migrations

Questions often test whether you can match the feature to the requirement. If the requirement is “move a running VM to another host for maintenance,” that is vMotion. If the requirement is “move a VM off a nearly full datastore without shutting it down,” that is Storage vMotion.

High Availability (HA)

Know exactly what HA does and does not do.

HA provides automated restart of VMs on surviving hosts after a host failure. It is not fault tolerance. It does not preserve the in-memory execution state of every VM after a host dies. It restarts workloads.

Study these HA ideas:

Host failure detection
Admission control purpose
Restart priority and VM monitoring concepts
Cluster dependence on shared resources and management configuration

A typical exam trap is confusing HA with DRS or FT. Keep them separate:

HA = restart after failure
DRS = placement and balancing
FT = continuous availability for specific workloads, conceptually different from restart-based protection

Distributed Resource Scheduler (DRS)

DRS balances workloads across hosts in a cluster based on resource demand and policy. You should know:

Why DRS exists
That it uses vMotion to rebalance when needed
The difference between initial placement and ongoing load balancing
Basic awareness of automation levels

Do not overcomplicate DRS for this exam. You are not being tested as a performance architect. Focus on the business outcome: better resource distribution and easier operations.

Resource controls

Many candidates skip this because it feels abstract. Do not.

Know the function of:

Reservations
Limits
Shares
Resource pools

At associate level, the exam usually wants you to understand intent:

A reservation guarantees a minimum amount of a resource.
A limit caps maximum consumption.
Shares influence priority when contention exists.
Resource pools help organize and allocate compute resources across grouped workloads.

What to practice

In a lab or demo environment:

Create a cluster
Enable HA and DRS
Migrate a powered-on VM with vMotion
Move VM storage with Storage vMotion
Edit resource settings on a VM or resource pool
Put a host into maintenance mode and observe migration options

If you understand what the cluster does during normal operations, maintenance, and failure, you are well aligned with this exam.

Network and storage objectives you cannot bluff

This is where many first-time candidates lose points. They recognize the terms but cannot distinguish one VMware construct from another.

vSphere networking

You must know the building blocks:

vSphere Standard Switch (VSS)
vSphere Distributed Switch (VDS)
Port groups
VMkernel adapters
Physical uplinks
Traffic types such as management, vMotion, and storage where relevant

Standard vs Distributed Switch

This comparison appears often.

VSS is configured per host.
VDS is centrally managed through vCenter and spans multiple hosts.

Know why an administrator would prefer a distributed switch in a larger environment:

Consistent networking configuration across hosts
Centralized management
Easier operations at scale

VMkernel adapters

Do not confuse a VM’s virtual NIC with a VMkernel adapter.

A VMkernel adapter supports host-level services such as:

Management traffic
vMotion traffic
Storage traffic for technologies that use VMkernel networking

You should be able to identify when a feature requires host networking configuration rather than guest networking.

VLANs and connectivity basics

At this level, understand the role of:

Port groups in applying network settings to VMs or VMkernel interfaces
VLAN tagging conceptually
Uplink redundancy and basic NIC teaming awareness

You do not need CCNP-level switching knowledge. You do need enough understanding to know how VMs and hosts connect to the physical network.

vSphere storage

Storage objectives usually center on VMware storage types and datastore behavior.

Study these specifically:

Datastores and what they store
VMFS
NFS datastores
Basic awareness of block vs file-based storage access
Shared storage importance for cluster features

Datastore concepts

A datastore is the logical storage container presented to ESXi for VM files. You should know what lives there:

Virtual disks (VMDK)
VM configuration files
Snapshots
Templates
ISO files in some environments

VMFS and NFS

Be able to distinguish them at a practical level:

VMFS is VMware’s clustered file system used on block storage presented to ESXi hosts.
NFS datastores use network file storage mounted by ESXi.

The exam is more likely to test use cases and architecture awareness than protocol internals.

Storage policy and mobility awareness

Depending on the exact item pool, you may see questions that touch on:

Why shared storage matters for mobility features
Datastore capacity considerations
Storage placement decisions
Basic purpose of Storage vMotion

Lab tasks for networking and storage

Practice these enough that the screens look familiar:

Create a standard switch and port group
Add or identify a VMkernel adapter for management or vMotion
Compare a host-level switch view with a distributed switch view in vCenter
Browse a datastore
Identify VM files in datastore storage
Migrate a VM between datastores

If a question asks whether something is a host networking function, a VM networking function, or a storage object, you should answer immediately.

Operations, lifecycle, and security basics VMware expects you to know

The exam is not a security certification, but VMware expects you to understand safe, normal administration.

Host lifecycle and maintenance

Know the purpose of:

Maintenance mode
Host patching and update concepts
Why hosts may need to be evacuated before planned work

You do not need advanced lifecycle manager mastery, but you should understand the operational sequence: prepare host, migrate workloads if needed, perform maintenance, return host to service.

Templates, clones, and deployment efficiency

This is common and straightforward if you have used VMware before.

Know the difference between:

Clone: a copy of an existing VM
Template: a master image used to deploy new VMs consistently

Understand when each is appropriate. Templates are about standardization and speed. Clones are often used for quick duplication.

Permissions and role-based access

At a basic level, study:

Users, groups, and roles
Permission assignment in vCenter inventory
Principle of least privilege conceptually

You may see questions asking who should receive rights at what level. You do not need to memorize every built-in role, but you should understand inheritance and scope.

Alarms, monitoring, and visibility

Know the purpose of VMware operational awareness features such as:

Alarms
Performance and status views in vCenter
Event/task history

The exam is more likely to ask what these are used for than to drill into every threshold setting.

Backups and snapshots

This deserves repetition because candidates regularly mix them up.

A snapshot is not a backup.
Snapshots are short-term state capture tools, often used before risky changes.
They are not a substitute for a proper backup product or protected recovery workflow.

Security basics

You should know practical hardening ideas without going deep into compliance frameworks:

Use centralized management and controlled permissions
Keep hosts and vCenter patched
Limit unnecessary access
Understand the role of certificates and secure management interfaces at a high level

For this exam, operational discipline matters more than memorizing security jargon.

A study plan that matches your VMware experience

This certification is not huge. Most candidates can prepare effectively in 2 to 5 weeks if they study with purpose.

If you are brand new to VMware: 4 to 5 weeks

Plan on 45 to 60 total hours.

Week 1

Learn vSphere architecture: ESXi, vCenter Server, inventory objects
Watch product overview videos
Create flash notes for VMware terminology

Week 2

Study VM creation, templates, cloning, snapshots, VMware Tools
Build or use a lab to create and manage VMs
Review permissions, folders, and basic administration

Week 3

Focus on clusters, HA, DRS, vMotion, Storage vMotion, maintenance mode
Practice migration workflows
Review resource pools, reservations, limits, shares

Week 4

Focus on networking and storage: VSS, VDS, port groups, VMkernel, VMFS, NFS, datastores
Do mixed review sessions using objective-based notes
Start timed practice questions

Week 5

Use the 97 Truekia practice questions to expose gaps
Re-read weak domains in official docs
Do two or three final review passes, not one giant cram session

If you already work with vSphere occasionally: 2 to 3 weeks

Plan on 20 to 30 total hours.

Your risk is overconfidence. You know how to click through common tasks, but the exam asks you to distinguish features precisely.

Use this order:

Review official objectives
Tighten architecture and terminology
Revisit networking/storage distinctions
Drill HA/DRS/vMotion prerequisites and use cases
Finish with practice questions and targeted rereading

If you are a sysadmin with regular VMware exposure: 1 to 2 weeks

Plan on 10 to 15 focused hours.

Do not spend all your time in the UI. Spend it on the terms and boundaries the exam likes to test:

What requires vCenter
Difference between HA, DRS, and FT
Difference between VSS and VDS
Difference between vMotion and Storage vMotion
Difference between snapshot, clone, and template
Difference between VMkernel networking and VM guest networking

Best order of study

For this exam, the cleanest order is:

Architecture and inventory
Virtual machines and administration basics
Clusters and mobility/availability features
Networking
Storage
Permissions, monitoring, and lifecycle
Practice questions and gap repair

That order works because each layer depends on the previous one.

Resources worth your time

Use fewer resources, but use better ones.

Official VMware resources

Start with VMware’s own material.

VMware Education Services exam guide / exam blueprint for 1V0-21.20 if still available through VMware certification pages
vSphere Product Documentation on VMware Docs for the version aligned with the exam era
vCenter Server and Host Management documentation
vSphere Networking documentation
vSphere Storage documentation
vSphere Availability documentation
vSphere Virtual Machine Administration documentation

These are not exciting reads, but they map closely to exam language.

VMware learning content

Good options include:

VMware vSphere: Install, Configure, Manage [V7] course materials if you can access them through your employer or training partner
VMware Hands-on Labs, especially labs covering vSphere, vCenter, and VM administration

Hands-on Labs are especially useful if you cannot build your own environment.

Books and broader references

For fundamentals, these are worth using selectively:

Mastering VMware vSphere 7 by Nick Marshall, Scott Lowe, and Forbes Guthrie
VMware vSphere 7 Clustering Deep Dive by Duncan Epping and Frank Denneman

The clustering book goes deeper than the associate exam requires, but it is excellent for truly understanding HA and DRS instead of memorizing them.

Video learning

If you learn better visually, use a reputable course from:

Pluralsight VMware vSphere fundamentals paths
LinkedIn Learning VMware vSphere introductory administration content
Official VMware videos and demo content where available

Do not rely on random short clips that skip terminology precision.

Practice resources

Your 97 Truekia practice questions should be used in the second half of your preparation, not on day one.
Build a weak-topic list from every missed question.
For each miss, tie it back to a VMware doc section or a lab task.

Best lab options

Pick one:

A small home lab with nested ESXi if you have the hardware
VMware Hands-on Labs if you do not
A shared work lab if your employer permits it

For this exam, even a modest environment is enough. You are not building a production cloud. You are learning object relationships and feature behavior.

How to use the 97 Truekia questions without wasting them

Practice questions are valuable only if you turn them into a feedback loop.

Use them in three passes.

Pass 1: diagnostic

Take 25 to 30 questions untimed.

Mark every miss into one of these buckets:

Architecture and inventory
VM administration
Cluster features
Networking
Storage
Permissions/operations

Do not retake immediately.

Pass 2: domain repair

After targeted study, do mixed sets of 15 to 20 questions.

For every wrong answer, write down:

The correct feature or term
Why your answer was wrong
What clue in the wording should have pointed you to the right choice

This matters for VMware exams because the wrong options are often plausible.

Pass 3: exam rehearsal

In your final week, do a timed full review session.

Your goal is not just score. It is speed and confidence on distinctions such as:

HA vs FT
VSS vs VDS
vMotion vs Storage vMotion
Template vs clone
Reservation vs limit vs shares

If you are still hesitating on those pairs, you are not ready yet.

VMware exam-day tactics for 1V0-21.20

VMware associate exams are usually fair, but they reward careful reading.

Before the exam

Review your short notes, not whole chapters
Revisit feature comparisons and prerequisites
Make sure you remember the exact purpose of the major components

During the exam

Read for the requirement, not the buzzwords.

Example patterns:

If the question asks about automatic restart after host failure, think HA.
If it asks about balancing workloads across hosts, think DRS.
If it asks about live migration of compute, think vMotion.
If it asks about moving VM files between datastores while powered on, think Storage vMotion.

Eliminate wrong answers aggressively

VMware questions often include options from the same product family that sound related. Remove answers that solve a different problem.

If you see all of these in one question:

HA n- DRS
vMotion
FT

ask yourself what the requirement is actually asking:

restart after failure?
continuous availability?
balancing?
migration?

That usually narrows it fast.

Watch for scope words

Pay attention to words like:

host
cluster
datastore
port group
VMkernel
vCenter

Those words tell you where the action happens.

Do not overthink associate-level items

If one answer is the clean, standard VMware feature that directly solves the stated problem, it is usually correct. This exam is more about accurate recognition than edge-case architecture debates.

Final checklist for the night before

Make sure you can answer these without notes:

What is the role of ESXi?
What does vCenter Server add?
What is a cluster used for?
What do HA and DRS each do?
What is the difference between vMotion and Storage vMotion?
What is the difference between VSS and VDS?
What is a VMkernel adapter used for?
What is the difference between VMFS and NFS in vSphere context?
Why is a snapshot not a backup?
When would you use a template instead of a clone?

If those answers are instant and clean, you are in good shape for vmware-1v0-2120.