Introducing the TCP/IP Internet Layer, IPv4 Addressing, and Subnets

Question 1

Provides information on the desired quality of service

Answer 1

Service type

Question 2

Limits the lifetime of a packet

Answer 2

Time to Live (TTL)

Question 3

Specifies the 32-bit binary value that represents the IPv4 address of the sending endpoint

Answer 3

Source address

Question 4

Specifies the 32-bit binary value that represents the IPv4 address of the receiving endpoint

Answer 4

Destination address

Question 5

Describes the version of IP

Answer 5

Version

Question 6

Describes the length of the header

Answer 6

Internet Header Length (IHL)

Question 7

Describes the length of a packet, including header and data

Answer 7

Total Length

Question 8

Used for unique fragment identification

Answer 8

Identification

Question 9

Sets various control flags regarding fragmentation

Answer 9

Flag

Question 10

Indicates where a specific fragment belongs

Answer 10

Fragment Offset

Question 11

Indicates the upper-layer protocol that is used in the data portion of an IPv4 packet. For example, a protocol value of 6 indicates this packet carries a TCP segment.

Answer 11

Protocol

Question 12

Used for header error detection

Answer 12

Header Checksum

Question 13

Includes optional parameters

Answer 13

Options

Question 14

Used to ensure that the header ends on a 32-bit boundary

Answer 14

Padding

Question 15

A Class A address block is designed to support extremely large networks with more than 16 million host addresses. The Class A address uses only the first octet (8 bits) of the 32-bit number to indicate the network address.

Answer 15

Class A

Question 16

The Class B address space is designed to support the needs of moderate to large networks with more than 65,000 hosts. The Class B address uses two of the four octets (16 bits) to indicate the network address.

Answer 16

Class B

Question 17

The Class C address space is the most commonly available address class. This address space is intended to provide addresses for small networks with a maximum of 254 hosts. In a Class C address, the first three octets (24 bits) of the address identify the network portion, with the remaining octet reserved for the host portion.

Answer 17

Class

Question 18

Class D (multicast) IPv4 addresses are dedicated to multicast applications such as streaming media. Multicasts are a special type of broadcast, in that only hosts that request to participate in the multicast group will receive the traffic to the IPv4 address of that group.

Answer 18

Class D

Question 19

Class E (reserved) IPv4 addresses are reserved by the IANA as a block of experimental addresses. Class E IPv4 addresses should never be assigned to IPv4 hosts. A Class E address begins with binary 1111.

Answer 19

Class E

Question 20

Because the network is not segmented, you can not apply security policies adapted to individual segments. If one device is compromised, it can quickly affect the whole network.

Answer 20

Security

Question 21

Isolation of network faults is more challenging especially in bigger flat networks, because there is no logical separation or hierarchy.

Answer 21

Troubleshooting

Question 22

In a large flat network you can end up with a lot of wasted IP addresses. You cannot use addresses from this network anywhere else.

Answer 22

Address space utilization

Question 23

A flat network represents a single Layer 2 broadcast domain. If there is a large amount of broadcast traffic this can impose a considerable pressure on the available resources. A single broadcast domain typically should not include more than a couple of hundred devices.

Answer 23

Scalability and speed

Question 24

The network address is a standard way to refer to a network. An IPv4 address that has binary zeros in all the host bit positions is reserved for the network address.

Answer 24

Network Address

Question 25

If an IPv4 device wants to communicate with all the devices on the local network, it sets the destination address to all ones (255.255.255.255) and transmits the packet. For example, hosts that do not know their network number will use the 255.255.255.255 broadcast address to ask a server for the network address.

Answer 25

Local Broadcast

Question 26

The broadcast IPv4 address of a network is a special address for each network that allows communication to all the hosts in that network. To send data to all the hosts in a network, a host can send a single packet that is addressed to the broadcast address of the network. For network 10.0.0.0/8, with 8 network bits, the broadcast address would be 10.255.255.255. This address is also referred to as the directed broadcast.

Answer 26

Directed Broadcast Address

Question 27

A local loopback address is used to let the system send a message to itself for testing. The loopback address creates a shortcut method for TCP/IP applications and services that run on the same device to communicate with one another. A typical local loopback IPv4 address is 127.0.0.1.

Answer 27

Local Loopback Address

Question 28

When neither a statically nor a dynamically configured IPv4 address is found on startup, those hosts supporting IPv4 link-local addresses (RFC 3927) will generate an address in the 169.254.0.0/16 range. This address can be used only for local network connectivity and operates with many caveats, one of which is that it will not be routed. You will mostly see this address as a failure condition when a PC fails to obtain an address via Dynamic Host Configuration Protocol (DHCP). This feature called Automatic Private IP Addressing (APIPA) is implemented in Microsoft and Apple Mac operating systems.

Answer 28

Autoconfiguration IPv4 Addresses

Question 29

Address blocks 198.51.100.0/24 and 203.0.113.0/24 are assigned for use in documentation and example code. They are often used along with example.com or example.net domain names in vendor and protocol documentation. As described in RFC 5737, addresses within these blocks do not legitimately appear on the public internet and can be used without any coordination with IANA or an internet registry.

Answer 29

IPv4 Addresses for Documentation

Question 30

The address 0.0.0.0 indicates the host in “this” network and is used only as a source address. An example use case is the DHCP assignment process before the host has a valid IPv4 address.

Answer 30

All Zeros Address