CompTIA Network+ (N10-008) – Chapter 1: Networking Fundamentals

These question-and-answer flashcards summarize the essential concepts, terms, protocols and technologies introduced in Chapter 1 of the CompTIA Network+ (N10-008) practice material, covering OSI layers, topologies, cable standards, IP addressing, ports & protocols, virtualization, WAN/cloud services, and related networking fundamentals.

At which OSI layer are MAC addresses used to identify devices on a LAN?

Layer 2 – Data Link

Which organization created the Open Systems Interconnection (OSI) reference model?

ISO – International Organization for Standardization

Which OSI layer handles logical addressing and routing of datagrams?

Layer 3 – Network

Name the two OSI layers whose protocols encapsulate application data to form a TCP/IP packet payload.

Layer 4 – Transport and Layer 7 – Application (plus Layers 5 & 6 as needed)

Which OSI layer is responsible for data translation, encryption and compression?

Layer 6 – Presentation

A router typically operates at which OSI layer?

Layer 3 – Network

Which OSI layer provides entry for user applications into the protocol stack?

Layer 7 – Application

Dialogue (session) control between two hosts occurs at which OSI layer?

Layer 5 – Session

Traditional Ethernet switches work at which OSI layer?

Layer 2 – Data Link (some multilayer switches also work at Layer 3)

TCP and UDP reside at which OSI layer? Connection-oriented or connectionless?

Layer 4 – Transport; TCP is connection-oriented, UDP is connectionless

Which OSI layer adds both a header and a trailer to create a frame?

Layer 2 – Data Link

What MAC layer access method does Ethernet use?

CSMA/CD (Carrier Sense Multiple Access with Collision Detection)

What is the Ethernet Maximum Transmission Unit (MTU)?

1500 bytes of payload (1518-byte frame including header/FCS)

Name two TCP flags used in the three-way handshake.

SYN and ACK

Which TCP flag begins session termination?

FIN

Which physical topology provides the most redundancy?

Mesh

What wired topology is most common in modern Ethernet LANs?

Star (hierarchical star)

Which topology strictly requires terminators at both ends of the cable?

Bus

Define LAN, MAN and WAN briefly.

LAN: Local, single building/campus; MAN: metro-scale city; WAN: long-distance between cities/regions

What is a SAN?

Storage Area Network – dedicated network that provides block-level storage access (often via Fibre Channel or iSCSI).

Name three wireless personal-area technologies.

Bluetooth, NFC, Z-Wave

List the four primary DSL variants people encounter.

ADSL, SDSL, VDSL, RADSL

What device marks the hand-off between customer and provider wiring?

Demarcation point (often houses a Smartjack / CSU/DSU)

Which leased-line speed is 44.736 Mbps and equals 28 T-1s?

T-3 (DS3)

Which U.S. optical WAN standard defines OC levels such as OC-3?

SONET (Synchronous Optical Network)

Multiplexing method that forwards packets based on labels instead of IP addresses?

MPLS – Multiprotocol Label Switching

DOCSIS applies to which Internet access technology?

Cable broadband

What cloud service models comprise IaaS, PaaS, SaaS, and DaaS?

Infrastructure, Platform, Software, and Desktop as a Service

Define NFV.

Network Function Virtualization – running network services (firewall, router, load balancer) as software on virtualized hardware (VNFs over NFVI, managed by NFV-MANO).

What is a hypervisor?

Software/firmware layer that creates and runs virtual machines by abstracting physical hardware (Type 1 bare-metal or Type 2 hosted).

Purpose of a vSwitch?

Virtual switch enabling VMs on same hypervisor (and beyond) to communicate, supporting VLANs, bridging, etc.

Which virtualization type runs directly on hardware without a host OS?

Type 1 (bare-metal) hypervisor

Copper twisted-pair categories supporting 10GBASE-T for 100 m segments?

Cat 6A, Cat 7 (Cat 8 supports 25/40 Gb at 30 m).

Which two fiber core types exist and which travels farther?

Single-mode (longer distances) and Multimode (shorter).

Common fiber-optic connector types (name four).

ST, SC, LC, MT-RJ (also MTP/MPO).

What distinguishes APC from UPC fiber connectors?

APC has angled polish (8°), green body, lower return loss; must mate with APC only.

Define SFP and QSFP.

Small Form-Factor Pluggable (1 Gb/10 Gb) and Quad SFP (4× increments e.g., 40 Gb).

Purpose of a patch panel.

Cable management hardware; terminates horizontal cabling to allow flexible cross-connects via patch cords.

TIA/EIA-568A & 568B standards specify what?

Pinout/color codes for 8-position RJ-45 connectors on twisted-pair cabling.

Which tool installs UTP wires into punchdown blocks?

Punchdown tool

Why are pairs twisted in UTP?

Reduce crosstalk and EMI by coupling equal and opposite fields.

Function of NAT vs PAT.

NAT translates private to public IPs; PAT (port address translation) maps many private hosts to one public address using unique port numbers.

Private IPv4 ranges (RFC 1918).

10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16

APIPA IPv4 range and purpose.

169.254.0.0/16; auto-assign when DHCP unavailable.

Dual-stack concept in IPv6 migration.

Running IPv4 and IPv6 simultaneously on hosts & routers.

IPv6 link-local prefix and typical use.

FE80::/10; automatic local-segment addressing, neighbor discovery.

Difference between unicast, multicast, anycast and broadcast.

Unicast: one-to-one. Multicast: one-to-many group. Anycast: one-to-nearest of many. Broadcast: one-to-all (IPv4 only).

CIDR enables what compared with classful addressing?

Variable-length subnet masks (VLSM) – any prefix size independent of class boundaries.

How many host bits remain in /24 network?

8 bits (256-2 = 254 hosts).

TCP/UDP well-known port for HTTPS.

443

Protocol/port pair for DNS queries.

UDP 53 (TCP 53 for zone transfers).

DHCP server listens on which ports?

UDP 67 (server) and UDP 68 (client).

Email protocols and their secure alternatives with default ports.

SMTP 25 (TLS 587), POP3 110 (SSL 995), IMAP4 143 (SSL 993).

Which protocol does Ping use?

ICMP (Echo Request/Reply).

Difference between FTP and TFTP.

FTP uses TCP 20/21, provides authentication & directory; TFTP uses UDP 69, simple unauthenticated file transfer.

What field in TCP options advertises segment size a host can accept?

MSS – Maximum Segment Size

What is a socket?

Combination of IP address and port number identifying a process-to-process connection (e.g., 192.168.1.5:80).

Connection-establishment process for TCP.

Three-way handshake: SYN → SYN/ACK → ACK.

UDP header size and key characteristic.

8 bytes; connectionless, no sequencing/acknowledgment.

Role of DNS record types A, AAAA, MX, CNAME.

A: IPv4 host; AAAA: IPv6 host; MX: mail exchanger; CNAME: alias.

What does TTL mean in DNS?

Time-To-Live – duration a resolver may cache a record.

NTP strata concept.

Defines distance from reference clock: Stratum 0 (source) → Stratum 1 servers → Stratum 2, etc.

Three-tier enterprise network architecture layers.

Core, Distribution (Aggregation), Access (Edge).

Define north-south vs east-west traffic flows.

North-south: between datacenter and external networks/users; East-west: between internal servers or VMs.

Spine-and-leaf design purpose.

Modern DC fabric providing predictable latency & bandwidth; spines connect all leaf switches.

VPN types of tunneling to carry IPv6 over IPv4.

6to4, Teredo, ISATAP (plus GRE/ IPsec tunnels).

GRE protocol number and purpose.

Protocol 47; encapsulates various network layer protocols over IP tunnels.

IPsec’s two main protocols.

AH (Authentication Header) and ESP (Encapsulating Security Payload).

What ports does SIP use for VoIP signalling (default/unsecure and secure)?

UDP/TCP 5060 (SIP) and 5061 (SIPS over TLS).

Which WAN technology traditionally uses PVCs and SVCs?

Frame Relay

Function of a Smartjack.

Provider-installed device at demarc for testing, signal conversion, loopback on leased lines (T-1/T-3).

CWDM vs DWDM difference.

CWDM uses wider wavelength spacing (less channels, cheaper); DWDM uses dense spacing (more channels, longer reach).

Purpose of PPPoE and typical use.

Encapsulates PPP frames inside Ethernet; used by DSL & fiber providers for authentication and per-user provisioning.

Service that resolves hostnames to IP addresses.

DNS – Domain Name System

Service that automatically assigns IP, subnet, gateway, etc., to clients.

DHCP – Dynamic Host Configuration Protocol

Explain SLAAC in IPv6.

Stateless Address Autoconfiguration – host forms its own address using router advertisements without a DHCPv6 server.

What is a VIP (Virtual IP)?

An IP address not tied to a single NIC; shared/translated (e.g., NAT public address, load-balancer front-end, floating cluster IP).

Define subinterface.

Logical interface created from a single physical NIC/port, often for multiple VLANs or point-to-point logical links.

Which port number does RDP use by default?

TCP/UDP 3389

Which layer of SDN is responsible for making forwarding decisions?

Control layer (controller)

Key benefit of infrastructure-as-code in cloud.

Automated, repeatable deployment & management of infrastructure using code/templates rather than manual configuration.