OCI Foundations - One-Page Cram Sheet¶

Architecture & Infrastructure¶

Regions - 40+ worldwide | Multi-AD (3 ADs) or Single-AD (1 AD + 3 FDs) | Format: us-phoenix-1

Availability Domains (ADs) - 1-3 per region | Physically separated data centers | AD# are customer-specific | For HA

Fault Domains (FDs) - 3 per AD | Logical hardware groupings | Protection against hardware failure

Tenancy & Compartments - Tenancy = root compartment | Max depth: 6 levels (root + 5) | Resources in 1 compartment, can move

Core Services Matrix¶

Networking Quick Reference¶

Gateways: - IG = Internet (bidirectional) - NAT = Outbound only (private subnets) - SGW = Oracle services (private, no internet) - DRG = On-premises (VPN/FastConnect)

Security: - Security Lists = Subnet-level, allow/deny, stateful - NSGs = Resource-level, allow only, stateful (PREFERRED)

Load Balancer: - Public or Private | Layer 4 (TCP) + Layer 7 (HTTP/HTTPS) | SSL termination | Health checks

IAM Policy Syntax¶

Allow <subject> to <verb> <resource-type> in <location>

Verbs (Permissions): inspect < read < use < manage

Examples:

Allow group Developers to manage instance-family in compartment Dev
Allow group DBAdmins to use database-family in tenancy
Allow dynamic-group AppServers to read secret-family in compartment Prod

Subjects: - Users/Groups = people - Dynamic Groups = resources (instances, functions)

Storage Decision Tree¶

Need block device for instance? → Block Volume
Need shared file system (NFS)? → File Storage
Unstructured data, frequent access? → Object Storage Standard
Unstructured data, occasional access? → Object Storage Infrequent Access
Long-term archive (10+ years)? → Archive Storage

Object Storage Tiers: - Standard = hot, instant, $$ - Infrequent Access = cool, instant, $ - Archive = cold, ~1hr retrieval, ¢

Database Quick Reference¶

Autonomous Database: - ATP = Transaction processing (OLTP) - ADW = Data warehouse (analytics/OLAP) - JSON = JSON documents - Serverless = shared infra, auto-scale - Dedicated = isolated infra, more control

DB Systems: - VM DB = virtual machines - Bare Metal DB = physical servers - Exadata DB = high-performance - RAC = High Availability (clustering) - Data Guard = Disaster Recovery (standby)

Security Services¶

Encryption: - All data encrypted at rest (default, Oracle-managed) - In transit via TLS/SSL - Customer-managed keys via Vault - BYOK = Bring Your Own Key

Observability¶

Monitoring = Metrics + Alarms (FREE) Logging = Audit + Service + Custom logs Notifications = Topics + Subscriptions (email, SMS, webhook) Events = State changes → trigger actions Tags = Cost tracking + organization

Pricing Models¶

Universal Credits = Use for any OCI service

Always Free Tier¶

Compute: 2 AMD VMs (⅛ OCPU, 1GB RAM) + 4 ARM cores (24GB RAM) Storage: 200GB Block + 10GB Object + 10GB Archive Database: 2 Autonomous DBs (20GB each) Networking: Load Balancer (10 Mbps), VCN, Monitoring, Logging

Trial: $300 credits, 30 days

High Availability Patterns¶

Single-AD Region:

AD-1
├── FD-1: Instance-1
├── FD-2: Instance-2
└── FD-3: Instance-3

Multi-AD Region:

AD-1: Web-1, App-1, DB-Primary
AD-2: Web-2, App-2, DB-Standby
AD-3: Web-3, App-3, DB-Backup

Exam Quick Facts¶

Numbers to Remember: - 60 questions, 90 minutes, 68% passing - Max compartment depth = 6 levels - Multi-AD region = 3 ADs - Single-AD region = 3 FDs - Block Volume max = 32 TB - Object max size = 10 TB - VCN CIDR = /16 to /30 - Always Free = 2 VMs, 4 ARM cores, 2 DBs

Architecture: - ADs = physically separated (different buildings) - FDs = logically separated (different racks) - AD numbers randomized per customer - Compartments = organization + access control + billing

Keywords in Questions: - "High availability" → Multi-AD or Multi-FD - "Most cost-effective" → Always Free, Object Storage, Serverless - "Lowest latency" → Region closest to users - "Secure" → Private subnets, NSGs, Vault - "On-premises" → DRG + FastConnect/VPN - "Unstructured data" → Object Storage - "Shared file system" → File Storage - "Long-term archive" → Archive Storage

Common Scenarios & Answers¶

Q: Design HA web app A: Multi-AD deployment + Load Balancer + DB replication

Q: Secure database credentials A: Store in Vault, use IAM policy to control access

Q: Private access to Object Storage A: Service Gateway (no internet required)

Q: Organize multi-project resources A: Compartments by project, then by environment (Dev/Test/Prod)

Q: Outbound internet for private subnet A: NAT Gateway

Q: Allow developers to manage VMs in Dev A: Allow group Developers to manage instance-family in compartment Dev

Q: Long-term log retention A: Archive Storage

Q: Frequently accessed user uploads A: Object Storage Standard tier

Q: Detect security threats automatically A: Cloud Guard

Q: Best DB for analytics workload A: Autonomous Data Warehouse (ADW)

Critical "Don't Forget" Items¶

✅ AD numbers are customer-specific (not the same for all) ✅ Compartments inherit policies from parents ✅ Security Lists = subnet, NSGs = resource ✅ NAT = outbound only (no inbound) ✅ Service Gateway = private (no internet needed) ✅ Dynamic Groups = resources, not users ✅ Archive Storage = ~1 hour retrieval time ✅ Autonomous DB has auto-scaling ✅ BYOL = Bring Your Own (Oracle) License ✅ Home region cannot be changed

Last-Minute Tips: 1. Read questions carefully - look for keywords 2. Eliminate obviously wrong answers first 3. Consider cost, security, and HA in scenarios 4. Watch for "MOST correct" vs just "correct" 5. Time: 1.5 minutes per question average 6. Flag uncertain questions, return later

Good luck! 🍀