What is the required standard or key value for: Application: HTTP, HTTPS, DNS, DHCP, FTP, SSH, SMTP (user-facing services) on the CompTIA Network+ (N10-009)?

Layer 7 (Handbook source: Domain 1.1 — OSI Model Architecture)

What is the required standard or key value for: Presentation: TLS/SSL, JPEG, GIF, ASCII (format translation, compression, encryption) on the CompTIA Network+ (N10-009)?

Layer 6 (Handbook source: Domain 1.1 — OSI Model Architecture)

What is the required standard or key value for: Session: RPC, NetBIOS, Sockets (session establishment, maintenance, and teardown) on the CompTIA Network+ (N10-009)?

Layer 5 (Handbook source: Domain 1.1 — OSI Model Architecture)

What is the required standard or key value for: 254 usable hosts (Mask: 255.255.255.0 · 256 total IPs) on the CompTIA Network+ (N10-009)?

/24 (Handbook source: Domain 1.4 — IPv4 Addressing & Subnetting)

What is the required standard or key value for: 126 usable hosts (Mask: 255.255.255.128 · 128 total IPs) on the CompTIA Network+ (N10-009)?

/25 (Handbook source: Domain 1.4 — IPv4 Addressing & Subnetting)

What is the required standard or key value for: 62 usable hosts (Mask: 255.255.255.192 · 64 total IPs) on the CompTIA Network+ (N10-009)?

/26 (Handbook source: Domain 1.4 — IPv4 Addressing & Subnetting)

What is the required standard or key value for: SSH (Secure Shell) & SFTP — TCP encrypted remote administration on the CompTIA Network+ (N10-009)?

Port 22 (Handbook source: Domain 1.5 — Ports and Protocols)

What is the required standard or key value for: DNS (Domain Name System) — UDP for queries, TCP for zone transfers on the CompTIA Network+ (N10-009)?

Port 53 (Handbook source: Domain 1.5 — Ports and Protocols)

What is the required standard or key value for: DHCP (Dynamic Host Configuration Protocol) — UDP (67 server, 68 client) on the CompTIA Network+ (N10-009)?

Port 67 / 68 (Handbook source: Domain 1.5 — Ports and Protocols)

What is the required standard or key value for: Gigabit Ethernet over Cat 5e/6 UTP copper up to 100 meters (IEEE 802.3ab) on the CompTIA Network+ (N10-009)?

1000BASE-T (Handbook source: Domain 1.2 — Media Types & Standards)

What is the required standard or key value for: 10 Gbps over Cat 6 (up to 55m) or Cat 6a (up to 100m) (IEEE 802.3an) on the CompTIA Network+ (N10-009)?

10GBASE-T (Handbook source: Domain 1.2 — Media Types & Standards)

What is the required standard or key value for: Gigabit Ethernet over multimode fiber (850nm wavelength) up to 550 meters on the CompTIA Network+ (N10-009)?

1000BASE-SX (Handbook source: Domain 1.2 — Media Types & Standards)

What is the required standard or key value for: Identify the problem (gather info, question users, identify symptoms, duplicate issue) on the CompTIA Network+ (N10-009)?

Step 1 (Handbook source: Domain 5.1 — Troubleshooting Methodology)

What is the required standard or key value for: Establish a theory of probable cause (question the obvious, consider top-to-bottom) on the CompTIA Network+ (N10-009)?

Step 2 (Handbook source: Domain 5.1 — Troubleshooting Methodology)

What is the required standard or key value for: Test the theory to determine cause (if confirmed proceed; if not, re-establish theory) on the CompTIA Network+ (N10-009)?

Step 3 (Handbook source: Domain 5.1 — Troubleshooting Methodology)

What key numbers, formulas, and standards are on the CompTIA Network+ (N10-009) cheat sheet?

Application: HTTP, HTTPS, DNS, DHCP, FTP, SSH, SMTP (user-facing services): Layer 7 (Domain 1.1 — OSI Model Architecture); Presentation: TLS/SSL, JPEG, GIF, ASCII (format translation, compression, encryption): Layer 6 (Domain 1.1 — OSI Model Architecture); Session: RPC, NetBIOS, Sockets (session establishment, maintenance, and teardown): Layer 5 (Domain 1.1 — OSI Model Architecture); 254 usable hosts (Mask: 255.255.255.0 · 256 total IPs): /24 (Domain 1.4 — IPv4 Addressing & Subnetting); 126 usable hosts (Mask: 255.255.255.128 · 128 total IPs): /25 (Domain 1.4 — IPv4 Addressing & Subnetting); 62 usable hosts (Mask: 255.255.255.192 · 64 total IPs): /26 (Domain 1.4 — IPv4 Addressing & Subnetting)

Can I download or print the CompTIA Network+ (N10-009) cheat sheet as a PDF?

Yes. Use the Print / Save as PDF button on this page to generate a clean, one-page printable reference sheet of every formula, normal value, standard, and rule tested on the CompTIA Network+ (N10-009).

Official 2026 Test Blueprint Reference

CompTIA Network+ (N10-009)/Cheat sheet

CompTIA Network+ (N10-009) cheat sheet: key rules and summary

Q: What are the common traps and tricky rules on the CompTIA Network+ (N10-009)?

CompTIA N10-009 uses 7 troubleshooting steps: Step 4 establishes a plan of action and identifies potential effects; Step 5 implements the solution. Never document findings (Step 7) before verifying full system functionality (Step 6).; Usable IPv4 host formula: Always subtract 2 from the total number of IP addresses (2^(32 - prefix) - 2) to exclude the network ID and broadcast address. A /30 subnet has 4 total IPs but only 2 usable host addresses.; Fiber optic modes: Multimode fiber (MMF) uses short-wave 850nm LED/VCSEL light sources and has larger core diameter (50/62.5 microns) for short building runs; single-mode fiber (SMF) uses 1310/1550nm laser optics with a 9-micron core for long hauls.

Maximum of 90 questions (multiple-choice and PBQs); 90 minutes; passing score 720 (scale 100–900).

Test yourself: 20 free questions Questions with answers

38 statutory numbers

5 core sections

4 rules people get wrong

100% handbook verified

Every line checked against the CompTIA Network+ N10-009 Certification Exam Objectives on September 24, 2026; sections added and read on October 26, 2026. Print it, or keep it open while you practice.

OSI 7-layer model & protocols

Essential

Layer 7: Application: HTTP, HTTPS, DNS, DHCP, FTP, SSH, SMTP (user-facing services)
Layer 6: Presentation: TLS/SSL, JPEG, GIF, ASCII (format translation, compression, encryption)
Layer 5: Session: RPC, NetBIOS, Sockets (session establishment, maintenance, and teardown)

IPv4 CIDR subnetting & private ranges

High-Yield

/24: 254 usable hosts (Mask: 255.255.255.0 · 256 total IPs)
/25: 126 usable hosts (Mask: 255.255.255.128 · 128 total IPs)
/26: 62 usable hosts (Mask: 255.255.255.192 · 64 total IPs)

Ethernet, fiber & wireless standards

Critical

1000BASE-T: Gigabit Ethernet over Cat 5e/6 UTP copper up to 100 meters (IEEE 802.3ab)
10GBASE-T: 10 Gbps over Cat 6 (up to 55m) or Cat 6a (up to 100m) (IEEE 802.3an)
1000BASE-SX: Gigabit Ethernet over multimode fiber (850nm wavelength) up to 550 meters

Interactive Visual Architecture

OSI 7-Layer Protocol Stack & PDU Hierarchy

CompTIA N10-009 tests the exact mapping between layer numbers, protocol data units (PDUs), and network protocols.

ApplicationPDU: Data

HTTP, HTTPS, DNS, DHCP, SSH, FTP, SMTP

PresentationPDU: Data

TLS/SSL, JPEG, GIF, ASCII, Data Compression

SessionPDU: Data

RPC, NetBIOS, Sockets, Session Teardown

TransportPDU: Segments

TCP (Connection), UDP (Connectionless), Ports

NetworkPDU: Packets

IPv4, IPv6, ICMP, ARP, Routers, Logical IPs

Data LinkPDU: Frames

Ethernet 802.3, MAC Addresses, Switches, NICs

PhysicalPDU: Bits

Cat 6, Fiber Optics, Hubs, Repeaters, Signals

OSI 7-layer model & protocols

Layer 7: Application: HTTP, HTTPS, DNS, DHCP, FTP, SSH, SMTP (user-facing services)Domain 1.1 — OSI Model Architecture
Layer 6: Presentation: TLS/SSL, JPEG, GIF, ASCII (format translation, compression, encryption)Domain 1.1 — OSI Model Architecture
Layer 5: Session: RPC, NetBIOS, Sockets (session establishment, maintenance, and teardown)Domain 1.1 — OSI Model Architecture
Layer 4: Transport: TCP, UDP (segments, end-to-end flow control, sequencing, port numbers)Domain 1.1 — OSI Model Architecture
Layer 3: Network: IP, ICMP, ARP (packets, routers, logical IP addressing, path determination)Domain 1.1 — OSI Model Architecture
Layer 2: Data Link: Ethernet 802.3, MAC addressing, switches, NICs (frames, physical addressing)Domain 1.1 — OSI Model Architecture
Layer 1: Physical: Cat 6, fiber optics, hubs, repeaters, transceivers (raw bit streams)Domain 1.1 — OSI Model Architecture

IPv4 CIDR subnetting & private ranges

/24: 254 usable hosts (Mask: 255.255.255.0 · 256 total IPs)Domain 1.4 — IPv4 Addressing & Subnetting
/25: 126 usable hosts (Mask: 255.255.255.128 · 128 total IPs)Domain 1.4 — IPv4 Addressing & Subnetting
/26: 62 usable hosts (Mask: 255.255.255.192 · 64 total IPs)Domain 1.4 — IPv4 Addressing & Subnetting
/27: 30 usable hosts (Mask: 255.255.255.224 · 32 total IPs)Domain 1.4 — IPv4 Addressing & Subnetting
/28: 14 usable hosts (Mask: 255.255.255.240 · 16 total IPs)Domain 1.4 — IPv4 Addressing & Subnetting
/29: 6 usable hosts (Mask: 255.255.255.248 · 8 total IPs)Domain 1.4 — IPv4 Addressing & Subnetting
/30: 2 usable hosts (Mask: 255.255.255.252 · 4 total IPs · point-to-point router links)Domain 1.4 — IPv4 Addressing & Subnetting
RFC 1918: Private ranges: 10.0.0.0/8 (Class A), 172.16.0.0/12 (Class B), 192.168.0.0/16 (Class C)Domain 1.4 — IPv4 Addressing & Subnetting
APIPA: 169.254.0.0/16 link-local auto-assigned address when DHCP fails (unroutable)Domain 1.4 — IPv4 Addressing & Subnetting

Network ports & core services

Port 22: SSH (Secure Shell) & SFTP — TCP encrypted remote administrationDomain 1.5 — Ports and Protocols
Port 53: DNS (Domain Name System) — UDP for queries, TCP for zone transfersDomain 1.5 — Ports and Protocols
Port 67 / 68: DHCP (Dynamic Host Configuration Protocol) — UDP (67 server, 68 client)Domain 1.5 — Ports and Protocols
Port 80 / 443: HTTP / HTTPS (Hypertext Transfer Protocol Secure) — TCPDomain 1.5 — Ports and Protocols
Port 88: Kerberos authentication protocol — TCP/UDP ticket-granting serviceDomain 1.5 — Ports and Protocols
Port 123: NTP (Network Time Protocol) clock synchronization — UDPDomain 1.5 — Ports and Protocols
Port 161 / 162: SNMP (Simple Network Management Protocol) — UDP (161 polling, 162 traps)Domain 1.5 — Ports and Protocols
Port 389 / 636: LDAP / LDAPS directory access service — TCP unencrypted / TLSDomain 1.5 — Ports and Protocols
Port 3389: RDP (Remote Desktop Protocol) — TCP/UDP graphical desktop sharingDomain 1.5 — Ports and Protocols

Ethernet, fiber & wireless standards

1000BASE-T: Gigabit Ethernet over Cat 5e/6 UTP copper up to 100 meters (IEEE 802.3ab)Domain 1.2 — Media Types & Standards
10GBASE-T: 10 Gbps over Cat 6 (up to 55m) or Cat 6a (up to 100m) (IEEE 802.3an)Domain 1.2 — Media Types & Standards
1000BASE-SX: Gigabit Ethernet over multimode fiber (850nm wavelength) up to 550 metersDomain 1.2 — Media Types & Standards
1000BASE-LX: Gigabit Ethernet over single-mode (1310nm up to 5 km) or multimode (up to 550m)Domain 1.2 — Media Types & Standards
Wi-Fi 6/6E: 802.11ax up to 9.6 Gbps · OFDMA & MU-MIMO · 2.4 GHz, 5 GHz, and 6 GHz (6E)Domain 1.3 — Wireless Standards
Wi-Fi 7: 802.11be Extremely High Throughput · 320 MHz channel width · Multi-Link OperationDomain 1.3 — Wireless Standards

CompTIA 7-step troubleshooting methodology

Step 1: Identify the problem (gather info, question users, identify symptoms, duplicate issue)Domain 5.1 — Troubleshooting Methodology
Step 2: Establish a theory of probable cause (question the obvious, consider top-to-bottom)Domain 5.1 — Troubleshooting Methodology
Step 3: Test the theory to determine cause (if confirmed proceed; if not, re-establish theory)Domain 5.1 — Troubleshooting Methodology
Step 4: Establish a plan of action to resolve problem and identify potential effectsDomain 5.1 — Troubleshooting Methodology
Step 5: Implement the solution or escalate as necessaryDomain 5.1 — Troubleshooting Methodology
Step 6: Verify full system functionality and implement preventive measuresDomain 5.1 — Troubleshooting Methodology
Step 7: Document findings, actions, and outcomes in knowledge baseDomain 5.1 — Troubleshooting Methodology

Second read · High failure rate

Rules People Get Wrong on Test Day

Questions on these specific handbook rules produce the highest error rates. Review these crucial distinctions carefully before test day.

TRAP 01

CompTIA N10-009 uses 7 troubleshooting steps

Step 4 establishes a plan of action and identifies potential effects; Step 5 implements the solution. Never document findings (Step 7) before verifying full system functionality (Step 6).

Handbook standard · Watch for negative phrasing (“Except”)

TRAP 02

Usable IPv4 host formula

Always subtract 2 from the total number of IP addresses (2^(32 - prefix) - 2) to exclude the network ID and broadcast address. A /30 subnet has 4 total IPs but only 2 usable host addresses.

Handbook standard · Watch for negative phrasing (“Except”)

TRAP 03

Fiber optic modes

Multimode fiber (MMF) uses short-wave 850nm LED/VCSEL light sources and has larger core diameter (50/62.5 microns) for short building runs; single-mode fiber (SMF) uses 1310/1550nm laser optics with a 9-micron core for long hauls.

Handbook standard · Watch for negative phrasing (“Except”)

TRAP 04

Loopback vs APIPA

127.0.0.1 (IPv4) and ::1 (IPv6) verify internal OS TCP/IP protocol stack functionality without transmitting packets to the NIC; receiving an APIPA address (169.254.x.x) means the client NIC functions but DHCP negotiation failed.

Handbook standard · Watch for negative phrasing (“Except”)

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