ITCA cheat sheet

ITCA Certification: Core Concepts Reference

• ITCA (Information Technology Certified Associate) is an entry-level credential from Certiport/CompTIA-style pathways that validates foundational IT literacy across hardware, software, networking, security, and operational support.

• OSI model layers in order: Physical, Data Link, Network, Transport, Session, Presentation, Application - mnemonic 'Please Do Not Throw Sausage Pizza Away'; each layer maps to specific devices (hubs=Layer 1, switches=Layer 2, routers=Layer 3).

• IPv4 private ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16; APIPA 169.254.0.0/16 indicates DHCP failure; loopback is 127.0.0.1; subnet mask /24 = 255.255.255.0 = 254 usable hosts.

• Storage: HDD uses spinning platters (mechanical, cheaper per GB), SSD uses NAND flash (no moving parts, faster, more shock-resistant); RAM is volatile working memory, ROM is non-volatile firmware storage.

• Security CIA triad: Confidentiality (encryption, access control), Integrity (hashing, checksums), Availability (redundancy, backups); authentication verifies identity, authorization determines permissions.

• Troubleshooting methodology order: identify the problem, establish a theory, test the theory, establish a plan of action, implement the solution, verify full functionality, document findings.

• Backup types: full (all data every time), incremental (changes since last backup of any type), differential (changes since last full backup); 3-2-1 rule = 3 copies, 2 media types, 1 offsite.

• Common ports: HTTP 80, HTTPS 443, FTP 20/21, SSH 22, Telnet 23, SMTP 25, DNS 53, DHCP 67/68, POP3 110, IMAP 143, RDP 3389.

• Virtualization and cloud service models: IaaS provides infrastructure, PaaS provides development platform, SaaS provides ready applications; hypervisor Type 1 runs on bare metal, Type 2 runs on a host OS.