Module 9: IPv4 and Network Segmentation

Question 1

9.1.1 Video - IPv4 Unicast

Unicast IP Transmission

Unicast IP transmission refers to one-to-one communication between network devices, where a packet is sent from a single source to a single destination.

Example of Unicast Transmission
- Source IP Address: 172.16.4.1 (a device sending the packet)
- Destination IP Address: 172.16.4.253 (a printer receiving the packet)
- The packet travels directly from one device to another, ensuring it is received only by the intended recipient.

Key Points About Unicast
1. Unicast packets have a specific destination IP address (not broadcast/multicast).
2. The source IP address is always unicast – a packet can only originate from a single device.
3. Unicast ensures direct device-to-device communication, commonly used for standard network traffic such as web browsing, file transfers, and remote desktop connections.

This method is different from broadcast (one-to-all) and multicast (one-to-many) transmissions, where packets are sent to multiple devices instead of a single destination.

Answer 1

Noted

Question 2

___ transmission refers to one device sending a message to one other device in one-to-one communications.

Answer 2

Unicast

Question 3

A unicast packet has a destination IP address that is a unicast address which goes to a ___ recipient.

Answer 3

single

Question 4

A source IP address can only be a ___ address, because the packet can only originate from a single source. This is regardless of whether the destination IP address is a unicast, broadcast, or multicast.

Answer 4

unicast

Question 5

The subnet mask for 255.255.255.0 is represented using slash notion or /24, indicating that the subnet mask is 24 ___ long.

Answer 5

bits

The subnet mask 255.255.255.0 in binary is 11111111.11111111.11111111.00000000.

Question 6

9.1.3 Video - IPv4 Broadcast

Broadcast Transmissions

A broadcast transmission is a type of network communication where a packet is sent from one device to all devices on the same network. This is achieved using a special broadcast IP address.

Example of a Broadcast Transmission
- Source IPv4 Address: 172.16.4.1 (the device sending the packet)
- Destination IPv4 Address: 255.255.255.255 (the broadcast address)

This special address ensures that the packet is received by all devices on the local network.

How Broadcast Works in a Network
1. The packet originates from 172.16.4.1.
2. The Ethernet switch floods the broadcast packet out to all ports except the source port.
3. Every device on the network receives the broadcast packet.
4. Routers do not forward broadcast packets to other networks, ensuring they remain within the local network.

Key Points About Broadcasts
- A broadcast packet is received by all devices in the network.
- Switches flood broadcast frames to all ports except the one it was received on.
- Routers block broadcast traffic to prevent it from spreading to other networks.
- Broadcasts are used for network discovery protocols, ARP requests, and DHCP requests.

Conclusion
Broadcast transmissions are essential for certain network operations, but excessive broadcasts can cause network congestion. That’s why modern networks often use multicast and unicast transmissions instead.

Answer 6

Noted

Question 7

___ transmission refers to a device sending a message to all the devices on a network in one-to-all communications.

Answer 7

Broadcast

Question 8

A broadcast packet has a destination IP address with all ___ in the host portion, or ___ bits.

Answer 8

ones (1s), 32 one (1)

Question 9

IPv4 uses ___. However, there are none of these on IPv6.

Answer 9

broadcast packets

Question 10

A broadcast packet must be processed by ___ devices in the ___ broadcast domain.

Answer 10

all, same

Question 11

A ___ identifies all hosts on the same network segment.

Answer 11

broadcast domain

Question 12

A broadcast may be ___ or ___.

Answer 12

directed, limited

Question 13

A ___ broadcast is sent to all hosts on a specific network.

Answer 13

directed

For example, a host on the 172.16.4.0/24 network sends a packet to 172.16.4.255.

Question 14

A ___ broadcast is sent to 255.255.255.255.

Answer 14

limited

By default, routers do not forward broadcasts.

Question 15

Broadcast packets use resources on the network and make every receiving host on the network process the packet. Therefore, broadcast traffic should be ___ so that it does not adversely affect the performance of the network or devices.

Answer 15

limited

Because routers separate broadcast domains, subdividing networks can improve network performance by eliminating excessive broadcast traffic.

Question 16

9.1.5 Video - IPv4 Multicast

Multicast Transmission

A multicast transmission is used to send a packet from a single device to a specific group of devices that are part of a multicast group. This is more efficient than broadcasting, as it prevents unnecessary delivery to devices that do not need the packet.

IPv4 Multicast Address Range
- Multicast addresses fall within the range:
224.0.0.0 to 239.255.255.255
- These addresses are reserved for multicast traffic, allowing selected devices to receive packets without flooding the entire network.

Example of Multicast Transmission
- Source IPv4 Address: 172.16.4.1 (the device sending the multicast packet)
- Destination IPv4 Multicast Group: Devices 172.16.4.3 and 172.16.4.4

How Multicast Works in a Network
1. The packet leaves 172.16.4.1 and is sent across the network.
2. Multiple devices receive the packet, but only those that belong to the multicast group (4.3 and 4.4) will process it.
3. Devices that are not part of the multicast group ignore the packet, preventing unnecessary network traffic.

Key Points About Multicast
- Multicast is more efficient than broadcast since it only reaches intended recipients.
- Devices must “subscribe” to a multicast group to receive the transmission.
- Used for applications like streaming, online gaming, and video conferencing where multiple devices need the same data.
- Routers can be configured to forward multicast traffic across networks using IGMP (Internet Group Management Protocol).

Conclusion
Multicast transmission optimizes network efficiency by targeting only specific devices in a group, reducing unnecessary traffic compared to broadcasting.

Answer 16

Noted

Question 17

___ transmission reduces traffic by allowing a host to send a single packet to a selected set of hosts that subscribe to a multicast group.

Answer 17

Multicast

Question 18

A multicast packet is a packet with a destination IP address that is a multicast address. IPv4 has reserved the ___ to ___ addresses as a multicast range.

Answer 18

224.0.0.0,
239.255.255.255

Question 19

Hosts that receive particular multicast packets are called ___.

Answer 19

multicast clients

The multicast clients use services requested by a client program to subscribe to the multicast group.

Question 20

Each multicast group is represented by a single IPv4 multicast ___. When an IPv4 host subscribes to a multicast group, the host processes packets addressed to this multicast address, and packets addressed to its uniquely allocated unicast address.

Answer 20

destination address

Question 21

Routing protocols such as ___ use multicast transmissions.

Answer 21

OSPF

For example, routers enabled with OSPF communicate with each other using the reserved OSPF multicast address 224.0.0.5. Only devices enabled with OSPF will process these packets with 224.0.0.5 as the destination IPv4 address. All other devices will ignore these packets.

Question 22

9.2.1 Public and Private IPv4 Addresses

Just as there are different ways to transmit an IPv4 packet, there are also different types of IPv4 addresses. Some IPv4 addresses cannot be used to go out to the internet, and others are specifically allocated for routing to the internet. Some are used to verify a connection and others are self-assigned. As a network administrator, you will eventually become very familiar with the types of IPv4 addresses, but for now, you should at least know what they are and when to use them.

Public IPv4 addresses are addresses which are globally routed between internet service provider (ISP) routers. However, not all available IPv4 addresses can be used on the internet. There are blocks of addresses called private addresses that are used by most organizations to assign IPv4 addresses to internal hosts.

In the mid-1990s, with the introduction of the World Wide Web (WWW), private IPv4 addresses were introduced because of the depletion of IPv4 address space. Private IPv4 addresses are not unique and can be used internally within any network.

Note: The long-term solution to IPv4 address depletion was IPv6.

Answer 22

Noted

Question 23

___ are addresses which are globally routed between internet service provider (ISP) routers.

Answer 23

Public IPv4 addresses

However, not all available IPv4 addresses can be used on the internet.

Question 24

Not all available IPv4 addresses can be used on the internet. There are blocks of addresses called ___ that are used by most organizations to assign IPv4 addresses to internal hosts.

Answer 24

private addresses

Question 25

In the mid-1990s, with the introduction of the World Wide Web (WWW), ___ were introduced because of the depletion of IPv4 address space.

Answer 25

private IPv4 addresses

Question 26

In the mid-1990s, with the introduction of the World Wide Web (WWW), private IPv4 addresses were introduced because of the depletion of ___.

Answer 26

IPv4 address space

Question 27

___ are not unique and can be used internally within any network.

Answer 27

Private IPv4 addresses

Question 28

The long-term solution to IPv4 address depletion was ___.

Answer 28

IPv6

Question 29

**Network Address and Prefix** | **RFC 1918 Private Address Range** 10.0.0.0/8 | 10.0.0.0 - 10.255.255.255 /// 172.16.0.0/12 | 172.16.0.0 - 172.31.255.255 /// 192.168.0.0/16 | 192.168.0.0 - 192.168.255.255

Answer 29

Noted

Question 30

Private addresses are defined in ___ and sometimes referred to as ___ address space.

Answer 30

RFC 1918,

Question 31

RFC 1918 Private Address Range

Answer 31

**Network Address and Prefix** | **RFC 1918 Private Address Range** 10.0.0.0/8 | 10.0.0.0 - 10.255.255.255 /// 172.16.0.0/12 | 172.16.0.0 - 172.31.255.255 /// 192.168.0.0/16 | 192.168.0.0 - 192.168.255.255 ## Footnote 10.x.x.x 172.16.x.x – 172.31.x.x 192.168.x.x

Question 32

Most internal networks, from large enterprises to home networks, use ___ for addressing all internal devices (intranet) including hosts and routers. However, these are not globally routable.

Answer 32

private IPv4 addresses ## Footnote For instance, customer networks 1, 2, and 3 are sending packets outside their internal networks. These packets have a source IPv4 address that is a private address and a destination IPv4 address that is public (globally routable). Packets with a private address must be filtered (discarded) or translated to a public address before forwarding the packet to an ISP.

Question 33

Before the ISP can forward this packet, it must translate the source IPv4 address, which is a private address, to a ___ using Network Address Translation (NAT).

Answer 33

public IPv4 address

Question 34

Before the ISP can forward this packet, it must translate the source IPv4 address, which is a private address, to a public IPv4 address using ___.

Answer 34

Network Address Translation (NAT) ## Footnote NAT is used to translate between private IPv4 and public IPv4 addresses. This is usually done on the router that connects the internal network to the ISP network. Private IPv4 addresses in the organization’s intranet will be translated to public IPv4 addresses before routing to the internet.

Question 35

There are certain addresses, such as the ___ and ___, that cannot be assigned to hosts. There are also ___ that can be assigned to hosts, but with restrictions on how those hosts can interact within the network.

Answer 35

network address, broadcast address, special addresses

Question 36

___ are special addresses used by a host to direct traffic to itself. Note: You will learn more about the ping command later in this course.

Answer 36

Loopback addresses (127.0.0.0 /8 or 127.0.0.1 to 127.255.255.254) ## Footnote They are more commonly identified as only 127.0.0.1. For example, the ping command is commonly used to test connections to other hosts. But you can also use the ping command to test if the IP configuration on your own device, as shown in the figure. Pinging the Loopback Interface C:∖Users∖NetAcad> ping 127.0.0.1 Pinging 127.0.0.1 with 32 bytes of data: Reply from 127.0.0.1: bytes=32 time<1ms TTL=128 Reply from 127.0.0.1: bytes=32 time<1ms TTL=128 Reply from 127.0.0.1: bytes=32 time<1ms TTL=128 Reply from 127.0.0.1: bytes=32 time<1ms TTL=128 Ping statistics for 127.0.0.1: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms C:∖Users∖NetAcad> ping 127.1.1.1 Pinging 127.1.1.1 with 32 bytes of data: Reply from 127.1.1.1: bytes=32 time<1ms TTL=128 Reply from 127.1.1.1: bytes=32 time<1ms TTL=128 Reply from 127.1.1.1: bytes=32 time<1ms TTL=128 Reply from 127.1.1.1: bytes=32 time<1ms TTL=128 Ping statistics for 127.1.1.1: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms C:∖Users∖NetAcad>

Question 37

___ are more commonly known as the Automatic Private IP Addressing (APIPA) addresses or self-assigned addresses.

Answer 37

Link-local addresses (169.254.0.0 /16 or 169.254.0.1 to 169.254.255.254)

Question 38

Link-local addresses (169.254.0.0 /16 or 169.254.0.1 to 169.254.255.254) are more commonly known as the ___ or ___.

Answer 38

Automatic Private IP Addressing (APIPA) addresses, self-assigned addresses

Question 39

They are used by a Windows client to self-configure in the event that the client cannot obtain an IP addressing through other methods.

Answer 39

Link-local addresses (169.254.0.0 /16 or 169.254.0.1 to 169.254.255.254)

Question 40

Link-local addresses can be used in a ___ connection but are not commonly used for this purpose.

Answer 40

peer-to-peer

Question 41

**9.2.5 Legacy Classful Addressing** In 1981, IPv4 addresses were assigned using classful addressing as defined in RFC 790 (https://tools.ietf.org/html/rfc790), Assigned Numbers. Customers were allocated a network address based on one of three classes, A, B, or C. The RFC divided the unicast ranges into specific classes as follows: * **Class A (0.0.0.0/8 to 127.0.0.0/8)** - Designed to support extremely large networks with more than 16 million host addresses. Class A used a fixed /8 prefix with the first octet to indicate the network address and the remaining three octets for host addresses (more than 16 million host addresses per network). * **Class B (128.0.0.0 /16 - 191.255.0.0 /16)** - Designed to support the needs of moderate to large size networks with up to approximately 65,000 host addresses. Class B used a fixed /16 prefix with the two high-order octets to indicate the network address and the remaining two octets for host addresses (more than 65,000 host addresses per network). * **Class C (192.0.0.0 /24 - 223.255.255.0 /24)** - Designed to support small networks with a maximum of 254 hosts. Class C used a fixed /24 prefix with the first three octets to indicate the network and the remaining octet for the host addresses (only 254 host addresses per network). Note: There is also a **Class D multicast block** consisting of **224.0.0.0 to 239.0.0.0** and a **Class E experimental address block** consisting of **240.0.0.0 - 255.0.0.0.** At the time, with a limited number of computers using the internet, classful addressing was an effective means to allocate addresses. As shown in the figure, Class A and B networks have a very large number of host addresses and Class C has very few. Class A networks accounted for 50% of the IPv4 networks. This caused most of the available IPv4 addresses to go unused. /// **Class A** - 50% **Class B** - 25% **Class C** - 12.5% **Class D & E** - 12.5% /// **Class A** Total Networks: 128 Total Hosts/Net: 16,777,214 **Class B** Total Networks: 16,384 Total Hosts/Net: 65,534 **Class C** Total Networks: 2,097,152 Total Hosts/Net: 254

Answer 41

Noted

Question 42

In the mid-1990s, with the introduction of the World Wide Web (WWW), classful addressing was deprecated to more efficiently allocate the limited IPv4 address space. Classful address allocation was replaced with ___, which is used today.

Answer 42

classless addressing

Question 43

___ ignores the rules of classes (A, B, C). Public IPv4 network addresses (network addresses and subnet masks) are allocated based on the number of addresses that can be justified.

Answer 43

Classless addressing

Question 44

Public IPv4 addresses are addresses which are globally routed over the internet. Public IPv4 addresses must be unique. Both IPv4 and IPv6 addresses are managed by the **Internet Assigned Numbers Authority (IANA)**. The IANA manages and allocates blocks of IP addresses to the **Regional Internet Registries (RIRs)**. The five RIRs are shown in the figure. RIRs are responsible for allocating IP addresses to ISPs who provide IPv4 address blocks to organizations and smaller ISPs. Organizations can also get their addresses directly from an RIR (subject to the policies of that RIR). * **AfriNIC** (African Network Information Centre) - Africa Region * **APNIC** (Asia Pacific Network Information Centre) - Asia/Pacific Region * **ARIN** (American Registry for Internet Numbers) - North America Region * **LACNIC** (Regional Latin-American and Caribbean IP Address Registry) - Latin America and some Caribbean Islands * **RIPE NCC** (Réseaux IP Européens Network Coordination Centre) - Europe, the Middle East, and Central Asia

Answer 44

Noted

Question 45

**Which two statements are correct about private IPv4 addresses? (Choose two).** ▢ Any organization (home, school, office, company) can use the 10.0.0.0/8 address. ▢ Private IPv4 addresses are assigned to devices within an organization’s intranet (internal network). ▢ 172.99.1.1 is a private IPv4 address. ▢ Internet routers will typically forward any packet with a destination address that is a private IPv4 address.

Answer 45

▢ Any organization (home, school, office, company) can use the 10.0.0.0/8 address. ▢ Private IPv4 addresses are assigned to devices within an organization’s intranet (internal network).

Question 46

**Which two statements are correct about public IPv4 addresses? (Choose two).** ▢ Public IPv4 address exhaustion is a reason why there are private Ipv4 addresses and why organizations are transitioning to IPv6. ▢ 192.168.1.10 is a public IPv4 address. ▢ Public IPv4 addresses are allowed to be assigned to devices within an organization’s intranet (internal network). ▢ To access a device over the internet, the destination IPv4 address must be a public address.

Answer 46

▢ Public IPv4 address exhaustion is a reason why there are private Ipv4 addresses and why organizations are transitioning to IPv6. ▢ To access a device over the internet, the destination IPv4 address must be a public address.

Question 47

**Which organization or group of organizations receives IP addresses from IANA and is responsible for allocating these addresses to ISPs and some organizations?** ◯ IETF ◯ Tier 1 ISPs ◯ IEEE ◯ RIRs

Answer 47

RIRs

Question 48

**9.3.2 Broadcast Domains and Segmentation** Have you ever received an email that was addressed to every person at your work or school? This was a broadcast email. Hopefully, it contained information that each of you needed to know. But often a broadcast is not really pertinent to everyone in the mailing list. Sometimes, only a segment of the population needs to read that information. In an **Ethernet LAN**, devices use **broadcasts** and the **Address Resolution Protocol (ARP)** to locate other devices. ARP sends Layer 2 broadcasts to a known IPv4 address on the local network to discover the associated MAC address. Devices on Ethernet LANs also locate other devices using services. A host typically acquires its IPv4 address configuration using the Dynamic Host Configuration Protocol (DHCP) which sends broadcasts on the local network to locate a DHCP server. Switches propagate broadcasts out all interfaces except the interface on which it was received. For example, if a switch in the figure were to receive a broadcast, it would forward it to the other switches and other users connected in the network.

Answer 48

Noted

Question 49

___ do not propagate broadcasts. When it receives a broadcast, it does not forward it out other interfaces.

Answer 49

Routers ## Footnote For instance, when R1 receives a broadcast on its Gigabit Ethernet 0/0 interface, it does not forward out another interface. Therefore, each router interface connects to a broadcast domain and broadcasts are only propagated within that specific broadcast domain.

Question 50

A large broadcast domain is a network that connects many hosts. A problem with a large broadcast domain is that these hosts can generate excessive ___ and negatively affect the network.

Answer 50

broadcasts ## Footnote In the figure, LAN 1 connects 400 users that could generate an excess amount of broadcast traffic. This results in slow network operations due to the significant amount of traffic it can cause, and slow device operations because a device must accept and process each broadcast packet.

Question 51

The solution is to reduce the size of the network to create smaller broadcast domains in a process called ___.

Answer 51

subnetting ## Footnote These smaller network spaces are called subnets. In the figure, the 400 users in LAN 1 with network address 172.16.0.0 /16 have been divided into two subnets of 200 users each: 172.16.0.0 /24 and 172.16.1.0 /24. Broadcasts are only propagated within the smaller broadcast domains. Therefore, a broadcast in LAN 1 would not propagate to LAN 2.

Question 52

These smaller network spaces are called ___.

Answer 52

subnets

Question 53

LAN 1: 172.16.0.0/24 (200 users) G0/0 LAN 2: 172.16.1.0/24 (200 users) G0/1 R1 Internet Notice how the prefix length has changed from a single /16 network to two /24 networks. This is the basis of subnetting: using ___ to create additional subnets.

Answer 53

host bits ## Footnote Note: The terms subnet and network are often used interchangeably. Most networks are a subnet of some larger address block.

Question 54

**9.3.4 Reasons for Segmenting Networks** Subnetting reduces overall network traffic and improves network performance. It also enables an administrator to implement security policies such as which subnets are allowed or not allowed to communicate together. Another reason is that it reduces the number of devices affected by abnormal broadcast traffic due to misconfigurations, hardware/software problems, or malicious intent. There are various ways of using subnets to help manage network devices. How network administrators can group devices and services into subnets: * **Location** (Floor Building) * **Group** or **Function** (Admin, HR, Students) * **Device Type** (Hosts, Servers, Printers)

Answer 54

Noted

Question 55

___ reduces overall network traffic and improves network performance. It also enables an administrator to implement security policies such as which subnets are allowed or not allowed to communicate together. Another reason is that it reduces the number of devices affected by abnormal broadcast traffic due to misconfigurations, hardware/software problems, or malicious intent.

Answer 55

Subnetting

Question 56

How network administrators can group devices and services into subnets: * ___ * ___ * ___

Answer 56

* **Location** (Floor Building) * **Group** or **Function** (Admin, HR, Students) * **Device Type** (Hosts, Servers, Printers) ## Footnote Network administrators can create subnets using any other division that makes sense for the network. Notice in each figure, the subnets use longer prefix lengths to identify networks. Understanding how to subnet networks is a fundamental skill that all network administrators must develop. Various methods have been created to help understand this process. Although a little overwhelming at first, pay close attention to the detail and, with practice, subnetting will become easier.

Question 57

**Which devices will not forward an IPv4 broadcast packet by default?** ◯ Ethernet switch ◯ router ◯ Windows PC ◯ None of the above. All devices forward IPv4 broadcast packets by default.

Answer 57

router

Question 58

**Which two situations are the result of excessive broadcast traffic? (Choose two)** ▢ when devices on all adjacent networks are affected ▢ slow network operations ▢ when the router has to forward an excessive number of packets ▢ slow device operations

Answer 58

slow network operations slow device operations

Question 59

# 9.4.1 What Did I Learn in this Module? **IPv4 Unicast, Broadcast, and Multicast** **Unicast transmission** refers to one device sending a message to one other device in one-to-one communications. A unicast packet has a destination IP address that is a unicast address which goes to a single recipient. A source IP address can only be a unicast address because the packet can only originate from a single source. This is regardless of whether the destination IP address is a unicast, broadcast or multicast. IPv4 unicast host addresses are in the address range of **1.1.1.1** to **223.255.255.255**. **Broadcast transmission** refers to a device sending a message to all the devices on a network in one-to-all communications. A broadcast packet has a destination IP address with all ones (1s) in the host portion, or 32 one (1) bits. A broadcast packet must be processed by all devices in the same broadcast domain. A broadcast may be directed or limited. A **directed broadcast** is sent to all hosts on a specific network. A **limited broadcast** is sent to **255.255.255.255**. By default, routers do not forward broadcasts. **Multicast transmission** reduces traffic by allowing a host to send a single packet to a selected set of hosts that subscribe to a multicast group. A multicast packet is a packet with a destination IP address that is a multicast address. IPv4 has reserved the **224.0.0.0** to **239.255.255.255** addresses as a multicast range. Each multicast group is represented by a single IPv4 multicast destination address. When an IPv4 host subscribes to a multicast group, the host processes packets addressed to this multicast address, and packets addressed to its uniquely allocated unicast address.

Answer 59

Noted

Question 60

# 9.4.1 What Did I Learn in this Module? **Types of IPv4 Addresses** **Public IPv4 addresses** are addresses which are globally routed between ISP routers. However, not all available IPv4 addresses can be used on the internet. There are blocks of addresses called **private addresses** that are used by most organizations to assign IPv4 addresses to internal hosts. Most internal networks, from large enterprises to home networks, use private IPv4 addresses for addressing all internal devices (intranet) including hosts and routers. However, private addresses are not globally routable. Before the ISP can forward this packet, it must translate the source IPv4 address, which is a private address, to a public IPv4 address using NAT. **Loopback addresses** **(127.0.0.0 /8 or 127.0.0.1 to 127.255.255.254)** are more commonly identified as only 127.0.0.1, these are special addresses used by a host to direct traffic to itself. **Link-local addresses** **(169.254.0.0 /16 or 169.254.0.1 to 169.254.255.254)** are more commonly known as the **Automatic Private IP Addressing (APIPA) addresses** or **self-assigned addresses**. They are used by a Windows DHCP client to self-configure in the event that there are no DHCP servers available. In 1981, IPv4 addresses were assigned using classful addressing as defined in RFC 790 (https://tools.ietf.org/html/rfc790), Assigned Numbers. Customers were allocated a network address based on one of **three classes**, A, B, or C. The RFC divided the unicast ranges into specific classes as follows: * **Class A (0.0.0.0/8 to 127.0.0.0/8)** - Designed to support extremely large networks with more than 16 million host addresses. * **Class B (128.0.0.0 /16 - 191.255.0.0 /16)** - Designed to support the needs of moderate to large size networks with up to approximately 65,000 host addresses. * **Class C (192.0.0.0 /24 - 223.255.255.0 /24)** - Designed to support small networks with a maximum of 254 hosts. * There is also a **Class D multicast block** consisting of **224.0.0.0 to 239.0.0.0** and a **Class E experimental address** block consisting of **240.0.0.0 - 255.0.0.0**. Public IPv4 addresses are addresses which are globally routed over the internet. Public IPv4 addresses must be unique. Both IPv4 and IPv6 addresses are managed by the*IANA. The **IANA** manages and allocates blocks of IP addresses to the RIRs. **RIRs** are responsible for allocating IP addresses to ISPs who provide IPv4 address blocks to organizations and smaller ISPs. Organizations can also get their addresses directly from an RIR.

Answer 60

Noted

Question 61

# 9.4.1 What Did I Learn in this Module? **Network Segmentation** In an Ethernet LAN, devices use **broadcasts** and **ARP** to locate other devices. ARP sends Layer 2 broadcasts to a known I**Pv4 address** on the local network to discover the associated MAC address. Devices on Ethernet LANs also locate other devices using services. A host typically acquires its IPv4 address configuration using **DHCP** which sends broadcasts on the local network to locate a DHCP server. **Switches** propagate broadcasts out all interfaces except the interface on which it was received. A **large broadcast domain** is a network that connects many hosts. A problem with a large broadcast domain is that these hosts can generate **excessive broadcasts** and negatively affect the network. The solution is to reduce the size of the network to create smaller broadcast domains in a process called **subnetting**. These smaller network spaces are called **subnets**. The basis of subnetting is to use host bits to create additional subnets. Subnetting reduces overall network traffic and improves network performance. It helps administrators to implement security policies such as which subnets are allowed or not allowed to communicate together. It reduces the number of devices affected by abnormal broadcast traffic due to misconfigurations, hardware/software problems, or malicious intent.

Answer 61

Noted

Question 62

**Quick Identification Rules** * 10.x.x.x → Private IP * 172.16.x.x – 172.31.x.x → Private IP * 192.168.x.x → Private IP * 127.x.x.x → Loopback * 169.254.x.x → Link-local (APIPA) * 224.x.x.x – 239.x.x.x → Multicast * 240.x.x.x – 255.x.x.x → Experimental * 255.255.255.255 → Broadcast

Answer 62

Noted

Question 63

**Which statement describes one purpose of the subnet mask setting for a host?** ◯ It is used to describe the type of the subnet. ◯ It is used to identify the default gateway. ◯ It is used to determine to which network the host is connected. ◯ It is used to determine the maximum number of bits within one packet that can be placed on a particular network.

Answer 63

It is used to determine to which network the host is connected.

Question 64

**What is one reason for subnetting an IP network?** ◯ to reduce the scope of broadcast flooding ◯ to increase the number of available host addresses on the network ◯ to remove the need for network services that rely on broadcasts, such as DHCP ◯ to ensure that all devices can communicate with each other without requiring a router

Answer 64

to reduce the scope of broadcast flooding

Question 65

**A message is sent to all hosts on a remote network. Which type of message is it?** ◯ limited broadcast ◯ multicast ◯ directed broadcast ◯ unicast

Answer 65

directed broadcast

Question 66

**A user is unable to access the company server from a computer. On issuing the ipconfig command, the user finds that the IP address of the computer is displayed as 169.254.0.2. What type of address is this?** ◯ private ◯ link-local ◯ loopback ◯ experimental

Answer 66

link-local

Question 67

**Which three IP addresses are private ? (Choose three.)** ▢ 10.1.1.1 ▢ 172.32.5.2 ▢ 192.167.10.10 ▢ 172.16.4.4 ▢ 192.168.5.5 ▢ 224.6.6.6

Answer 67

10.1.1.1 172.16.4.4 192.168.5.5

Question 68

**Match each description with an appropriate IP address.** ▢ 240.2.6.255 ▢ 127.0.0.1 ▢ 198.133.219.2 ▢ 169.254.1.5 Options: ▢ an experimental address ▢ a loopback address ▢ a link-local address ▢ a public address

Answer 68

**240.2.6.255** an experimental address **127.0.0.1** a loopback address **198.133.219.2** a public address **169.254.1.5** a link-local address

Question 69

**Which network device can serve as a boundary to divide a Layer 2 broadcast domain?** ◯ router ◯ Ethernet bridge ◯ Ethernet hub ◯ access point

Answer 69

router

Question 70

**What is the role of IANA?** ◯ maintaining standards related to electrical wiring and connectors ◯ documenting developments for new protocols and updating existing protocols ◯ managing the allocation of IP addresses and domain names ◯ promoting the development and evolution of the Internet around the world

Answer 70

managing the allocation of IP addresses and domain names

Question 71

**Which address prefix range is reserved for IPv4 multicast?** ◯ 240.0.0.0 - 254.255.255.255 ◯ 224.0.0.0 - 239.255.255.255 ◯ 169.254.0.0 - 169.254.255.255 ◯ 127.0.0.0 - 127.255.255.255

Answer 71

224.0.0.0 - 239.255.255.255

Question 72

**A high school in New York (school A) is using videoconferencing technology to establish student interactions with another high school (school B) in Russia. The videoconferencing is conducted between two end devices through the internet. The network administrator of school A configures the end device with the IP address 209.165.201.10. The administrator sends a request for the IP address for the end device in school B and the response is 192.168.25.10. Neither school is using a VPN. The administrator knows immediately that this IP will not work. Why?** ◯ This is a loopback address. ◯ This is a link-local address. ◯ This is a private IP address. ◯ There is an IP address conflict.

Answer 72

This is a private IP address.

Question 73

**A host is transmitting a broadcast. Which host or hosts will receive it?** ◯ all hosts in the same network ◯ a specially defined group of hosts ◯ the closest neighbor on the same network ◯ all hosts on the internet

Answer 73

all hosts in the same network