Introduction to IP

CompTIA A+ 220-1101 – 2.1

Why is TCP considered a “reliable” form of delivery?

TCP is reliable because it checks for errors and resends lost or damaged data. or if there's an error during communication, it can resend the data to make sure everything gets through correctly.

TCP and UDP take place at what OSI layer?

OSI layer 4 or transport layer

multiplexing

putting several signals together to send them through one line.

Connection oriented protocol

A formal connection before data is sent and closes it after (like TCP).

Is UDP connection oriented or connectionless?

There’s no formal opening or closing of a connection before sending data. or UDP is connectionless — it just sends data without setting up a connection.

is UDP considered "reliable"?

UDP is considered unreliable, not because the data is more likely to be lost, but because it doesn’t check for errors or resend lost data. It just sends the data and doesn’t guarantee delivery.

IPv4 sockets

An IPv4 socket is made of an IP address + port number + protocol. This combo identifies who’s talking and what app they’re using on both ends.

non ephemeral ports

Non-ephemeral ports are permanent port numbers from 0 to 1,023. They are usually assigned to specific well-known applications (like HTTP uses port 80, or HTTPS uses port 443).

ephemeral ports

Ephemeral ports (1,024–65,535) are temporary ports picked by the client just for that session.

What do NIC (Network Interface cards) do specficliy?

NICs are designed for specific network types like Ethernet, WAN, or wireless.

How are network interface cards (NIC) put into a computer?

NICs are either on the motherboard or added as an expansion card.

what does a repeater do?

A repeater receives a signal, regenerates it (strengthens or cleans it up), and resends it. It doesn't make any forwarding decisions.

What’s a hub?

A hub is a device that receives traffic on one port and repeats it to every other port on the hub. It sends the same signal to all devices connected to it.

All communication on a hub operates at…..?

half duplex, so it can only send or receive data, not both at the same time.

What is a bridge?

A bridge connects networks and forwards traffic based on MAC addresses, unlike a hub that sends data to all ports.

what does a switch do?

A switch sends traffic to the right port based on the destination MAC address.

How does a switch perform lookups?

A switch performs lookups using a piece of hardware called an ASIC (Application-Specific Integrated Circuit), which allows it to quickly examine and forward traffic based on the destination MAC address.

what is a multilayer switch?

A multilayer switch is a device that combines the functions of both a switch and a router. It switches traffic based on MAC addresses like a switch, but it can also route traffic based on IP addresses like a router.

what’s an unmanaged switch

An unmanaged switch is a basic switch with very few configuration options. requires no setup just plug in your devices and they can start communicating.

what can a managed switch do?

A managed switch allows you to configure VLANs, set up trunking (802.1Q) to connect multiple switches, prioritize traffic, and support redundancy using STP (Spanning Tree Protocol). It can communicate with a network management station using SNMP (Simple Network Management Protocol). For troubleshooting, you can also use port mirroring to monitor network traffic.

port mirroring

Port mirroring copies network traffic from one port and sends it to another port for monitoring.

whats a router?

A router sends data between networks by using IP addresses to decide where it should go.

what do you call a router that’s integrated into a switch?

A multilayer switch or Layer 3 switch is a device that acts as both a switch and a router.

does a router connect diverse network types?

Yes, a router connects diverse network types, such as LANs (Local Area Networks), WANs (Wide Area Networks), and different physical media like copper and fiber.

what is a wireless access point?

A Wireless Access Point (WAP) is a device that acts as a bridge, extending a wired network onto a wireless network. It allows devices to connect wirelessly to the network and makes forwarding decisions based on the MAC address.

what is a wireless LAN controller?

A Wireless LAN Controller (WLC) is a device that provides centralized management of Wireless Access Points (WAPs). It helps with tasks like deploying new access points, monitoring performance and security, configuring and deploying changes to all sites, and generating reports on access point usage.

is a wireless LAN controller usually a proprietary system?

Yes, a Wireless LAN Controller (WLC) is usually a proprietary system. Most WLCs are designed by specific manufacturers and are typically used with their own wireless access points and network devices.

Is it true that wireless LAN controllers cannot be cloud-based?

No, it's not true that Wireless LAN Controllers (WLCs) cannot be cloud-based. In fact, many modern WLCs are cloud-managed or have cloud-based options, allowing centralized management of wireless networks from anywhere.

whats a firewall do?

A firewall is a security device that controls traffic in and out of a network. Traditional firewalls filtered traffic by TCP or UDP port numbers, but modern firewalls (called next-generation firewalls) can inspect the entire traffic flow, including the applications being used.

can firewalls be routers?

Firewalls can be routers—many modern firewalls have routing capabilities built in. These firewalls can sit at the edge of the network (handling ingress and egress traffic) and perform tasks like routing and network address translation (NAT) using their internal routing engine.

What is a cable modem?

A cable modem connects your home or business to the internet through a broadband connection provided by a cable company. It uses a standard called DOCSIS (Data Over Cable Service Interface Specification) to send and receive data over the cable TV network.

what kind of throughput do DOCSIS(Data Over Cable Service Interface Specification) networks support?

DOCSIS can handle speeds from a few megabits up to over a gigabit per second, depending on the version and network setup. But gigabit speeds (1,000 Mb/s and higher) are also possible and are becoming more common with newer versions like DOCSIS 3.1.

do DOCSIS networks support multiple services? if so, what services?

yes. video (cable), data (internet), and voice (telephone)

Yes, DOCSIS lets one cable line carry TV, internet, and phone service at the same time.

what is a DSL (digital subscriber line) modem?

A DSL modem uses your phone line to connect to the internet, with faster downloads than uploads. It’s often called ADSL (Asymmetric Digital Subscriber Line) because the download speed is faster than the upload speed—that’s what “asymmetric” means.

What makes DSL (digital subscriber line) asymmetric?

DSL is asymmetric because it gives you more download speed than upload speed. This matches how most people use the internet—we download more (like streaming or browsing) than we upload.

what is a challenge of DSL(digital subscriber line)?

A challenge of DSL is the distance limitation—the farther you are from the central office (the service provider's local facility), the slower the speeds become. This happens because the signal degrades over long distances on the telephone lines.

what kind of throughput does DSL provide?

DSL can offer up to 52 Mb/s for downloads and 16 Mb/s for uploads, but the speed depends on how far you are from the provider.

What’s a patch panel?

A patch panel is where Ethernet cables are connected in the network closet. It allows for easy connections between your networking equipment and various network points using patch cables.

what is PoE (power over ethernet)?

PoE (Power over Ethernet) is a technology that allows network devices (like phones, cameras, or access points) to receive both data and power through a single Ethernet cable. The power is typically supplied by a PoE-enabled switch or injector.

What are endspans?

Endspans refer to Ethernet connections where power is supplied directly from the switch to the network device, typically using PoE (Power over Ethernet). In this setup, the switch itself provides both data and power through a single Ethernet cable.

What are midspans?

Midspans are used when a device requires PoE (Power over Ethernet), but the switch cannot provide it. A PoE injector is placed between the switch and the device, injecting power into the Ethernet cable so the device can receive both power and data.

what is EoP (ethernet over power)?

EoP lets you send Ethernet data over your power lines, making it easier to extend your network without needing new Ethernet cables.

What is the EoP (ethernet over power) designed for and what’s an example?

EoP (Ethernet over Power) is designed for devices that aren’t typically connected to Ethernet—using existing power lines to provide network connectivity. An example is electric cars, where the car can be connected to the Ethernet network when plugged in to charge, without needing an extra Ethernet cable.

What is IPv4?

IPv4 (Internet Protocol version 4) is a protocol that uses 32-bit addresses to identify devices on the internet.

What is IPv6

IPv6 (Internet Protocol version 6) uses 128-bit addresses, providing a massive increase in the number of possible IP addresses compared to IPv4.

What is a Private IP address?

A Private IP address is used only within private networks and cannot be routed or accessed over the Internet. These addresses are typically assigned to devices within local networks like homes or businesses.

What is a Public IP address?

A Public IP address is used on both private and public networks. It can be routed over the Internet and must be unique across the globe to avoid conflicts.

What is NAT?

NAT ( Network Address Translation) changes private IP addresses to public ones when communicating with the Internet, allowing multiple devices to use a single public IP.

What is IPv6 Link-Local?

IPv6 Link-Local addresses are used automatically within a local network and cannot be used to communicate outside of that network. They start with fe80::/64.

What is IPv6 Site-Local?

IPv6 Site-Local addresses are used only within an organization and cannot be routed over the Internet. They start with fc00::/7.

What is IPv6 Global?

IPv6 Global addresses are public, unique, and used for communication over the Internet.

What is Unicast?

Unicast is when data is sent from one device to just one other device.

What is Multicast?

Multicast sends data from one device to a group of devices that want to receive it.

What is Anycast?

Anycast sends data to the nearest device in a group of possible receivers.

What is a Broadcast?

Broadcast sends data to every device in the same LAN (used only in IPv4).