CompTIA Network+ Domain 1

What is the OSI model?

A seven-layer reference model for network communication.

OSI Layer 1 — Physical

Transmits raw bits through physical media and signals.

OSI Layer 2 — Data Link

Handles frames, MAC addresses, and local-link delivery.

OSI Layer 3 — Network

Handles logical IP addressing and routing between networks.

OSI Layer 4 — Transport

Provides end-to-end transport, segmentation, and port addressing.

OSI Layer 5 — Session

Establishes, manages, and terminates communication sessions.

OSI Layer 6 — Presentation

Translates, formats, encrypts, and compresses data.

OSI Layer 7 — Application

Provides network services directly to applications.

What is a router?

A device that forwards packets between IP networks.

What is a switch?

A device that forwards frames using MAC addresses.

What is a firewall?

A device or software that filters traffic using security rules.

What is an IDS?

An intrusion detection system that identifies suspicious activity and alerts.

What is an IPS?

An intrusion prevention system that detects and blocks malicious activity.

What is a load balancer?

Distributes requests across multiple servers or resources.

What is a proxy?

An intermediary that forwards requests between clients and other systems.

What is NAS?

Network-attached storage provides file-level storage over a network.

What is SAN?

A storage area network provides block-level storage access to servers.

What is a wireless access point?

A device that connects wireless clients to a network.

What is a wireless controller?

A system that centrally manages multiple wireless access points.

What is a CDN?

A content delivery network distributes content through geographically dispersed servers.

What is a VPN?

A virtual private network creates a protected connection over an untrusted network.

What is QoS?

Quality of service prioritizes traffic to meet performance requirements.

What is TTL?

Time to live limits a packet's lifetime or a record's caching duration.

What is NFV?

Network functions virtualization runs network services as software instead of dedicated appliances.

What is a VPC?

A virtual private cloud is an isolated virtual network in a cloud environment.

What are network security groups?

Virtual firewall rules that control allowed inbound and outbound traffic for cloud resources.

What are network security lists?

Rules that control ingress and egress traffic for cloud network subnets or resources.

What is an internet gateway?

A cloud gateway that enables eligible resources to communicate with the internet.

What is a NAT gateway?

A gateway that lets private-network resources initiate outbound connections without public IPs.

What is AWS Direct Connect?

A dedicated network connection between an organization and AWS.

What is a public cloud deployment?

Cloud infrastructure offered to multiple customers over shared provider infrastructure.

What is a private cloud deployment?

Cloud infrastructure dedicated to one organization.

What is a hybrid cloud deployment?

An environment combining private infrastructure with public cloud resources.

What is SaaS?

Software as a service delivers ready-to-use applications over a network.

What is IaaS?

Infrastructure as a service provides virtualized compute, storage, and networking resources.

What is PaaS?

Platform as a service provides a managed environment for building and deploying applications.

What is scalability?

The ability to increase or decrease capacity to meet demand.

What is elasticity?

The ability to dynamically adjust resources as demand changes.

What is multitenancy?

Multiple customers share underlying infrastructure with logical isolation.

What is FTP?

File Transfer Protocol transfers files; it commonly uses TCP ports 20 and 21.

What is SFTP?

Secure File Transfer Protocol transfers files over SSH, typically using TCP port 22.

What is SSH?

Secure Shell provides encrypted remote access over TCP port 22.

What is Telnet?

An unencrypted remote terminal protocol that typically uses TCP port 23.

What is SMTP?

Simple Mail Transfer Protocol sends email; the listed port is TCP 25.

What is DNS?

Domain Name System resolves domain names and other DNS records; it uses port 53.

What is DHCP?

Dynamic Host Configuration Protocol automatically assigns IP settings; it uses UDP ports 67 and 68.

What is TFTP?

Trivial File Transfer Protocol provides simple file transfers over UDP port 69.

What is HTTP?

Hypertext Transfer Protocol transfers web content; its default port is TCP 80.

What is NTP?

Network Time Protocol synchronizes system clocks, typically using UDP port 123.

What is SNMP?

Simple Network Management Protocol monitors and manages devices on UDP ports 161 and 162.

What is LDAP?

Lightweight Directory Access Protocol accesses directory services, typically on port 389.

What is HTTPS?

HTTP secured with TLS, typically using TCP port 443.

What is SMB?

Server Message Block provides network file and printer sharing, typically on TCP port 445.

What is Syslog?

A protocol for transmitting system logs, commonly using UDP port 514.

What is SMTP submission?

Authenticated email submission commonly uses TCP port 587.

What is LDAPS?

LDAP secured with TLS, typically using TCP port 636.

What is Microsoft SQL Server's default port?

TCP port 1433.

What is RDP?

Remote Desktop Protocol provides remote graphical access, typically on TCP/UDP port 3389.

What is SIP?

Session Initiation Protocol manages communication sessions, commonly on ports 5060 and 5061.

What is ICMP?

Internet Control Message Protocol carries network diagnostic and error messages.

What is TCP?

Transmission Control Protocol provides reliable, ordered, connection-oriented delivery.

What is UDP?

User Datagram Protocol provides connectionless delivery without guaranteed reliability or ordering.

What is GRE?

Generic Routing Encapsulation tunnels network-layer packets inside other packets.

What is IPsec?

A suite of protocols that protects IP traffic through authentication and/or encryption.

What is IPsec AH?

Authentication Header provides integrity and data-origin authentication, but not encryption.

What is IPsec ESP?

Encapsulating Security Payload can provide confidentiality, integrity, and authentication.

What is IKE?

Internet Key Exchange negotiates security associations and keys for IPsec.

What is unicast traffic?

Traffic sent from one source to one destination.

What is multicast traffic?

Traffic sent from one source to a subscribed group of destinations.

What is anycast traffic?

Traffic sent to the nearest or best destination among multiple systems sharing an address.

What is broadcast traffic?

Traffic sent from one source to all hosts on the local broadcast domain.

What is IEEE 802.11?

The IEEE family of standards for wireless LAN networking.

What is cellular networking?

Wireless communication using geographically divided cells and cellular base stations.

What is satellite networking?

Communication that uses satellites to relay signals over long distances.

What is IEEE 802.3?

The IEEE family of Ethernet networking standards.

Single-mode vs. multimode fiber

Single-mode supports longer distances; multimode is typically used for shorter distances.

What is DAC?

Direct attach copper is a short-reach copper cable assembly used for high-speed links.

What is twinaxial cable?

A cable with two inner conductors and shielding, commonly used in DAC assemblies.

What is coaxial cable?

A cable with a central conductor, insulation, and shielding.

What is plenum-rated cable?

Cable designed to meet stricter fire and smoke requirements for plenum spaces.

What is non-plenum cable?

Cable not rated for plenum spaces unless installation conditions and local code permit it.

What is an Ethernet transceiver?

A component that transmits and receives Ethernet signals over a specified medium.

What is a Fibre Channel transceiver?

A transceiver designed for Fibre Channel storage networking.

What is an SFP?

A small form-factor pluggable transceiver module for network connections.

What is a QSFP?

A quad small form-factor pluggable module supporting multiple high-speed lanes.

What is an SC connector?

A push-pull fiber-optic connector with a square-shaped housing.

What is an LC connector?

A small-form-factor fiber-optic connector with a latch.

What is an ST connector?

A fiber-optic connector that uses a bayonet-style twist lock.

What is an MPO connector?

A multi-fiber push-on connector that terminates multiple optical fibers.

What is an RJ11 connector?

A registered-jack connector commonly used for telephone lines.

What is an RJ45 connector?

An eight-position connector commonly used with twisted-pair Ethernet cabling.

What is an F-type connector?

A threaded coaxial connector commonly used for cable television and broadband.

What is a BNC connector?

A bayonet-locking coaxial connector used in RF and legacy networking applications.

What is a mesh topology?

A topology where nodes connect to multiple other nodes for redundancy.

What is a hybrid topology?

A network design combining two or more topology types.

What is a star topology?

Devices connect to a central switch or hub.

What is a spine-and-leaf topology?

A data-center design where leaf switches connect to spine switches.

What is a point-to-point topology?

A dedicated link connects exactly two endpoints.

What is the core layer?

The high-speed backbone interconnecting distribution layers in a three-tier network.

What is the distribution layer?

The layer that aggregates access switches and applies routing or policy.