Infrastructure Networking: Tier 1

What is a hub?

A network device that sends incoming data to all other connected ports.

What is a switch?

A network device that connects devices in a LAN and forwards Ethernet frames using MAC addresses.

What is a router?

A network device that connects different IP networks and forwards packets using IP addresses.

What is a modem?

A device that converts signals as required to communicate with an ISP’s transmission system.

What is an access point (AP)?

A device that allows wireless devices to connect to a network, usually through Wi-Fi.

What is a firewall?

A hardware or software system that filters network traffic according to security rules.

What is a NIC?

A Network Interface Card that allows a device to transmit and receive network data.

What is a server?

A hardware device or software program that provides services, data, or resources to clients.

What is the main difference between a hub and a switch?

A hub sends data to all connected ports, while a switch forwards frames toward the appropriate destination port.

What is the main difference between a switch and a router?

A switch primarily connects devices within a LAN using MAC addresses, while a router forwards packets between IP networks using IP addresses.

What is the difference between a modem and a router?

A modem connects to an ISP’s transmission system, while a router forwards traffic between networks.

What is the difference between an access point and a router?

An access point provides wireless access to a network, while a router forwards traffic between networks.

What is the OSI model?

A seven-layer reference model used to understand and troubleshoot network communication.

What is OSI Layer 7?

Application: provides network services to applications such as web browsers and email clients.

What is OSI Layer 6?

Presentation: handles data representation, translation, encryption, and compression in the OSI model.

What is OSI Layer 5?

Session: establishes, manages, synchronizes, and terminates communication sessions.

What is OSI Layer 4?

Transport: provides end-to-end communication between applications and supports segmentation and delivery.

What is OSI Layer 3?

Network: forwards packets between networks using logical addresses such as IP addresses.

What is OSI Layer 2?

Data Link: transfers frames over a local link and uses MAC addresses for local delivery.

What is OSI Layer 1?

Physical: transmits raw bits through electrical, optical, or radio signals.

What is the OSI model order from Layer 7 to Layer 1?

Application, Presentation, Session, Transport, Network, Data Link, Physical.

What mnemonic helps remember the OSI layers from Layer 7 to Layer 1?

All People Seem To Need Data Processing.

At which OSI layer does TCP operate?

Layer 4: Transport.

At which OSI layer does UDP operate?

Layer 4: Transport.

At which OSI layer does IP operate?

Layer 3: Network.

At which OSI layer do MAC addresses operate?

Layer 2: Data Link.

At which OSI layer do cables and electrical signals operate?

Layer 1: Physical.

At which OSI layer does a router primarily operate?

Layer 3: Network.

At which OSI layer does an Ethernet switch primarily operate?

Layer 2: Data Link.

What is TCP?

Transmission Control Protocol; a connection-oriented transport protocol that provides reliable, ordered data delivery.

What is UDP?

User Datagram Protocol; a connectionless transport protocol with low overhead that does not guarantee delivery or ordering.

What is the main difference between TCP and UDP?

TCP provides reliable, ordered delivery, while UDP has lower overhead and does not guarantee delivery or ordering.

What does connection-oriented mean in TCP?

TCP establishes a connection before normal data transfer.

What does connectionless mean in UDP?

UDP sends datagrams without establishing a TCP-style connection first.

How does TCP provide reliability?

It uses acknowledgments and retransmits missing data when necessary.

Why is UDP useful for time-sensitive applications?

It has lower overhead and does not require built-in retransmission or ordered delivery.

What are common uses of TCP?

Web browsing, email, file transfers, and many remote-access applications.

What are common uses of UDP?

Online gaming, voice and video calls, live streaming, and DNS queries.

What is the TCP three-way handshake?

A three-step process that establishes a TCP connection.

What is the correct TCP three-way handshake sequence?

SYN → SYN-ACK → ACK.

What does SYN mean?

A TCP flag used to initiate or participate in establishing a connection.

What does SYN-ACK mean?

A response that acknowledges the connection request and indicates the receiver’s own connection request.

What does ACK mean?

A TCP flag indicating that the acknowledgment field is valid.

What is an IP address?

A logical network-layer address used to identify an endpoint for communication across networks.

What is a MAC address?

A link-layer address used to identify a network interface for local-link communication.

What is the main difference between an IP address and a MAC address?

An IP address supports communication between networks, while a MAC address supports local-link delivery.

What is the typical length of an IPv4 address?

32 bits.

What is the typical length of an Ethernet MAC address?

48 bits.

What format does IPv4 use?

Four decimal octets separated by dots, such as 192.168.1.10.

What format does a MAC address usually use?

Six hexadecimal octets, such as C8-96-65-E4-53-58.

What is a point-to-point topology?

A topology that directly connects two devices through a dedicated link.

What is a bus topology?

A topology in which multiple devices share one main cable.

What is another name for bus topology?

Line topology.

What is a major disadvantage of bus topology?

A break in the main cable can disrupt communication across the network.

What is a star topology?

A topology in which every device connects to a central switch or hub.

What is an advantage of star topology?

A single device or its cable can fail without usually affecting the other connected devices.

What is a disadvantage of star topology?

If the central switch or hub fails, communication between connected devices may be disrupted.

What is a ring topology?

A topology in which devices are connected in a circular path.

What is a disadvantage of ring topology?

A link or device failure can disrupt communication unless redundancy is provided.

What is a mesh topology?

A topology in which devices have multiple interconnections or paths.

What is a full mesh topology?

Every device has a direct connection to every other device.

What is a partial mesh topology?

Only some devices have direct connections to multiple other devices.

What is an advantage of mesh topology?

Multiple paths provide redundancy and alternative routes when a link fails.

What is a disadvantage of mesh topology?

It can be expensive and complex because it requires many connections.

What is the difference between physical and logical topology?

Physical topology describes the actual arrangement of devices and cables; logical topology describes how data flows.

What is IPv4?

Internet Protocol version 4; uses 32-bit addresses written as four decimal octets.

What is IPv6?

Internet Protocol version 6; uses 128-bit addresses written in hexadecimal groups separated by colons.

What is the main difference between IPv4 and IPv6?

IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses and provides a vastly larger address space.

How many bits are in one IPv4 octet?

8 bits.

What are the binary place values for an 8-bit octet?

128, 64, 32, 16, 8, 4, 2, 1.

What is 192 in 8-bit binary?

11000000, because 128 + 64 = 192.

What is 255 in 8-bit binary?

11111111.

What is 0 in 8-bit binary?

00000000.

What does a subnet mask do?

It identifies which bits of an IPv4 address represent the network and which represent the host.

What does the subnet mask 255.255.255.0 mean?

The first 24 bits are network bits and the last 8 bits are host bits.

How do you calculate usable IPv4 host addresses in a typical subnet?

Use 2^h - 2, where h is the number of host bits.

How many usable host addresses are in a typical /24 IPv4 subnet?

254 usable addresses.

What are the three private IPv4 address ranges?

10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

What is a private IP address?

An IPv4 address reserved for private networks and not directly routed across the public Internet.

What is a public IP address?

An IP address used for public Internet routing.

What is NAT?

Network Address Translation; translates IP addresses and commonly allows multiple private IPv4 devices to share one public IPv4 address.

What is DHCP?

Dynamic Host Configuration Protocol; automatically provides IP configuration to network devices.

What is DNS?

Domain Name System; translates domain names into IP addresses and supports other DNS queries.

What is the difference between DHCP and DNS?

DHCP provides network configuration, while DNS resolves domain names to IP addresses.

What is simplex transmission?

Communication in one direction only.

What is half-duplex transmission?

Both devices can transmit and receive, but not at the same time.

What is full-duplex transmission?

Both devices can transmit and receive simultaneously.

What is an example of simplex transmission?

A traditional radio broadcast.

What is an example of half-duplex transmission?

A walkie-talkie.

What is an example of full-duplex transmission?

A telephone conversation.

What is data encapsulation?

The process of adding protocol information to data as it moves down the network layers.

What is the typical encapsulation order?

Application data → TCP segment or UDP datagram → IP packet → link-layer frame → bits.

What is decapsulation?

The process of removing and processing protocol information as data moves up the receiving device’s network layers.

What is a TCP segment?

A transport-layer data unit containing a TCP header and application data.

What is a UDP datagram?

A transport-layer data unit containing a UDP header and application data.

What is an IP packet?

A network-layer data unit that carries data and IP addressing information.

What is an Ethernet frame?

A data-link-layer data unit that carries an IP packet across a local network link.