AWS 092: Shared, dedicated and host tenancy
The real problem
A team recognizes the name Shared, dedicated and host tenancy but has not connected the feature to a real requirement, identity boundary, network or data path, failure mode, price dimension, and cleanup owner. A plausible configuration could still fail the workload.
Final outcome
The learner will produce a requirement-led artifact for Shared, dedicated and host tenancy, inspect the matching AWS control plane in the Management Console, run a matching CloudShell or AWS CLI query, interpret the output, diagnose one failure, defend one architecture choice, and prove cleanup or approved retained state.
The practical outcome is not a command transcript. It must show what was expected, what happened, what the result proves, what it does not prove, and which evidence would change the decision.
Learning objectives
By the end of this lesson, the learner can:
- explain shared tenancy is the default;
- explain dedicated instances isolate hardware by account;
- explain dedicated hosts expose a physical server;
- explain host affinity can preserve placement;
- explain tenancy affects compatibility and cost;
- connect control-plane state to the real data, network, identity, or application behavior;
- identify cost and cleanup ownership before any optional mutation;
- troubleshoot from evidence without opening broad access or adding broad permissions.
Relationship model
Requirement
|
v
Identity and policy -> AWS configuration -> network or data path -> workload behavior
| | | |
+--------------------+----------------------+--------------------+
|
v
monitoring, cost, recovery, cleanup
Use this model to separate an AWS object that exists from a result that actually works. Every arrow is a verification boundary.
Prerequisites, permissions, Region, and safety
- Learning baseline: This sequence assumes practical Linux knowledge but no prior cloud-computing or AWS knowledge. Cloud, networking, security, data, automation, and architecture concepts must come from completed earlier lessons. If a prerequisite checkpoint is incomplete, return to its linked lesson before continuing.
- Confirm a non-root caller with
aws sts get-caller-identityand keep the account number private. - Use
ap-south-1unless this lesson explicitly names a second Region. - Confirm the intended profile and Region with
aws configure listbefore interpreting an empty result. - Use read-only List, Get, and Describe permissions for the named services. Design exercises run locally and require no resource-creation permission.
- This is a no-create lesson. Console and CLI work is read-only, and every design artifact is created locally.
- Never publish account IDs, public addresses, ARNs containing private account data, session IDs, presigned URLs, object data, credentials, or KMS material.
- Do not use root, world-open SSH or RDP, disabled TLS verification, unowned resources, or irreversible retention controls in a training exercise.
Core model
| Concept | What the learner must understand |
|---|---|
| Shared tenancy is the default | Instances run on hardware shared with other AWS accounts while the hypervisor provides isolation. It offers the broadest instance choice and normal pricing. |
| Dedicated Instances isolate hardware by account | They run on single-tenant hardware, but AWS controls host placement and the customer does not receive host socket, core, or host-ID visibility needed for some licenses. |
| Dedicated Hosts expose a physical server | The account allocates an entire server with visibility and control over sockets, cores, host ID, and instance placement, supporting selected compliance and BYOL needs. |
| Host affinity can preserve placement | A stopped instance can be configured to restart on the same Dedicated Host when affinity and capacity allow, which matters for licenses tied to physical host identity. |
| Tenancy affects compatibility and cost | Not every instance type, feature, or purchase option works with every tenancy. Dedicated Host and Dedicated Instance charges follow distinct pricing models. |
| Nitro isolation is strong on shared hardware | Dedicated tenancy is not automatically required for security. Choose it only when a licensing, contractual, regulatory, or documented isolation requirement demands physical dedication. |
How it works
Translate the requirement precisely: dedicated hardware, visibility into sockets and cores, control of instance placement, host-bound licenses, or simply logical isolation. Dedicated Host is usually the answer when physical-host license accounting matters; Dedicated Instances alone may not supply that control.
Read the result in layers:
- Scope: account, Region, VPC, bucket, AZ, endpoint, principal, object version, or resource ARN.
- Control plane: the requested configuration exists and reached an expected state.
- Behavior: the request, connection, health check, replication, restore, or application result meets the requirement.
- Operations: monitoring, failure owner, cost, retention, rollback, and cleanup are known.
Control-plane success is necessary but not sufficient. A resource can be available while policy, routing, DNS, health, data, or application behavior remains wrong.
Architecture decision table
| Requirement | Preferred direction | Why |
|---|---|---|
| Ordinary cloud-native workload | Shared tenancy | It provides isolation without paying for unused dedicated hardware. |
| Requirement says single-tenant hardware only | Dedicated Instances or Hosts after feature comparison | Both can provide dedicated hardware, but operational control differs. |
| BYOL license is tied to sockets or physical server | Dedicated Host | Host visibility and placement control support license accounting. |
| Need AWS to manage host placement without co-tenants | Dedicated Instances | The account receives dedicated hardware without host-level allocation control. |
Professional questions normally contain several valid services. State the requirement that selects one option, why the nearest alternative fails it, and what changed requirement would reverse the choice.
AWS Management Console guided practice
Before opening a service page, write the expected account, Region, starting state, and evidence. Do not choose Create, Save, Purchase, Lock, or Delete unless the lesson explicitly authorizes the live track.
- Open EC2 Dedicated Hosts and inspect host state, Availability Zone, instance family, sockets, cores, capacity, and running instances.
- Open an EC2 instance Placement details and compare default, dedicated, and host tenancy fields.
- Match the selected tenancy to the written compliance or software-license requirement before allocating paid dedicated hardware.
For each step, capture the field name and value in text. A screenshot may support the record but does not replace the explanation. Console labels can evolve, so use the service search and current documentation if a navigation label differs.
CloudShell and AWS CLI practice
CloudShell is the default browser-based command environment taught in AWS 028. AWS 029 and AWS 030 cover local CLI installation and authentication. This lesson therefore does not assume that an unconfigured local shell is ready.
Start every session with:
export AWS_DEFAULT_REGION="ap-south-1"
aws sts get-caller-identity --query Arn --output text
aws configure list
Redact the account portion of the ARN before sharing. Then perform the topic query:
Inspect instance tenancy and host identifiers before applying licensing assumptions.
aws ec2 describe-instances --instance-ids i-0123456789abcdef0 --query 'Reservations[0].Instances[0].Placement.{Tenancy:Tenancy,HostId:HostId,Affinity:Affinity,Group:GroupName}'
aws ec2 describe-hosts --query 'Hosts[].{Host:HostId,AZ:AvailabilityZone,State:State,Family:HostProperties.InstanceFamily,Sockets:HostProperties.Sockets,Cores:HostProperties.TotalVCpus}' --output table
Expected interpretation:
Tenancy host indicates a Dedicated Host. Confirm the exact license terms and supported configurations; technology alone cannot interpret the vendor agreement.
Replace every replace-with-... sample value before running its command, and use only an explicitly owned resource. Explain each option first. These queries are read-only; a successful response does not authorize a later create or delete operation.
Practical work
Create p05-tenancy-decision.md. Compare default tenancy, dedicated instances, and Dedicated Hosts for shared hardware policy, sockets and cores, host affinity, license management, supported instance families, recovery, host resource groups, capacity planning, and current cost. Select default tenancy for P05 unless a documented compliance or licensing requirement changes it.
The evidence package must contain:
- the problem and final requirement in the learner's own words;
- caller type and Region with private identifiers redacted;
- exact planned values, ownership, and cost class;
- one Console observation and matching CLI or API evidence;
- one behavior result or supplied data-plane record;
- one denied, failed, or counterexample result and evidence-led diagnosis;
- one architecture choice plus the rejected alternative;
- cleanup proof or explicit retained-state owner, expiry, and next lesson.
Verification standard
Use expected state before observed state. Record timestamps in UTC and preserve the original failure before changing anything. A passing submission answers all four questions:
- What exact requirement was tested?
- Which evidence proves the AWS configuration?
- Which evidence proves the workload behavior?
- What remains unproven or requires later monitoring?
If AWS returns no rows, verify account, Region, permission, filters, pagination, resource type, and deletion state before concluding that nothing exists.
Common failures and troubleshooting
| Symptom | Evidence first | Likely boundary | Smallest safe response |
|---|---|---|---|
| object appears missing | caller, Region, filters, pagination, tags | scope or read permission | align scope before creating a duplicate |
| state remains pending or unavailable | service state, events, dependencies, quotas | dependency or capacity | correct the named dependency and wait with a bound |
| AccessDenied | principal, action, resource, explicit-deny context | identity, resource, endpoint, organization, or KMS policy | change only the proven policy layer |
| configuration exists but behavior fails | route, DNS, security, listener, health, logs, object version | data path or application | test the next boundary and change one control |
| bill is higher than expected | hours, bytes, requests, AZs, addresses, retention | cost model or retained resource | stop optional work and reconcile the ledger |
| cleanup is blocked | dependency inventory and owning service | deletion order or immutable state | remove owned dependants in reviewed reverse order |
Do not troubleshoot by attaching administrator access, opening administration ports to the internet, disabling encryption, retrying uncontrolled creation, deleting unknown resources, or weakening retention.
Cost, cleanup, and retained state
No AWS resource is created. Close CloudShell and remove or redact downloaded evidence.
Cleanup evidence requires terminal state and an after-inventory. Search related ENIs, public IPv4 addresses, EBS volumes and snapshots, load balancers, target groups, Auto Scaling instances, endpoints, logs, S3 versions and delete markers, backup recovery points, and global IAM roles when they apply. Billing data can lag, so schedule a later review.
Architecture and certification decisions
- Certification coverage: SAA-C03; SOA-C03; SAP-C02; DOP-C02.
- Exam mapping: SAA D2-D4.
- Explain service scope, failure boundary, consistency, recovery, security, operations, and price rather than matching a keyword.
- Treat availability and durability, encryption and authorization, routing and filtering, health and lifecycle, backup and replication, and discount and capacity as separate concepts.
- Do not reproduce protected certification questions.
Knowledge check
- Which model exposes sockets, cores, and host ID?
Expected direction: Dedicated Hosts.
- Does shared tenancy mean no isolation?
Expected direction: No. AWS hypervisor isolation separates customers on shared hardware.
- Are Dedicated Instances and Dedicated Hosts identical?
Expected direction: No. Hosts provide physical-server allocation and placement visibility; Dedicated Instances do not.
- Should every sensitive workload use a Dedicated Host?
Expected direction: No. Use it for an actual compliance, contract, or licensing requirement.
Completion gate and assessment
| Area | Points | Passing evidence |
|---|---|---|
| Requirement and model | 15 | Correct scope, terminology, and final outcome |
| Console evidence | 15 | Current path and interpreted fields |
| CLI or API evidence | 15 | Scoped command, expected result, and limitations |
| Behavior or decision exercise | 20 | Reproducible result or defensible architecture reasoning |
| Troubleshooting | 15 | Original symptom, hypothesis, one change, retest, rollback |
| Security and cost | 10 | Least privilege, data protection, current price dimensions |
| Cleanup and handoff | 10 | Terminal-state proof or approved retained-state record |
Pass at 80 out of 100 with no critical safety failure. A missing practical artifact, unexplained output, unsafe access, destructive action outside the owned scope, unplanned billed resource, or false cleanup claim requires remediation and a changed retest.