Module 1 - 03-3 Flashcards
Local and wide network communication
What does IP stand for?
Internet protocol (IP)
Define Internet Protocol (IP) address
A unique string of characters that identifies a location of a device on the internet
How many types of IP addresses are there?
Two (2)
What are the types of IP addresses?
- IP version 4 (IPv4)
- IP version 6 (IPv6)
Briefly explain IPv4
IPv4 addresses are written as four, 1, 2, or 3-digit numbers separated by a decimal point
(Example: 19.117.63.126).
In the early days of the internet, IP addresses were all IPV4. But as the use of the internet grew, all the IPv4 addresses started to get used up, so IPv6 was developed.
IPv4 addresses are made up of four decimal numbers separated by periods, each number ranging from 0 to 255. Together the numbers span 4 bytes, and allow for up to 4.3 billion possible addresses.
An example of an IPv4 address would be: 198.51.100.0.
Briefly explain IPv6
IPv6 addresses are made up of 32 characters
(Example: 684D:1111:222:3333:4444:5555:6:77).
The length of the IPv6 address will allow for more devices to be connected to the internet without running out of addresses as quickly as IPv4.
IPv6 addresses are made of eight hexadecimal numbers separated by colons, each number consisting of up to four hexadecimal digits. Together, all numbers span 16 bytes, and allow for up to 340 undecillion addresses (340 followed by 36 zeros).
An example of an IPv6 address would be: 2002:0db8:0000:0000:0000:ff21:0023:1234.
Note: to represent one or more consecutive sets of all zeros, you can replace the zeros with a double colon “::”, so the above IPv6 address would be “2002:0db8::ff21:0023:1234.”
IP addresses can be either ____ or ____.
public or private
Briefly explain a Public IP address
Your internet service provider assigns a public IP address that is connected to your geographic location.
When network communications goes out from your device on the internet, they all have the same public-facing address.
Just like all the roommates in one home share the same mailing address, all the devices on a network share the same public-facing IP address.
Briefly explain a Private IP address
Private IP addresses are only seen by other devices on the same local network.
This means that all the devices on your home network can communicate with each other using unique IP addresses that the rest of the internet can’t see.
What is another kind of address used in network communications?
MAC address
What does MAC stand for?
Media Access Control
Define MAC address
A unique alphanumeric identifier that is assigned to each physical device on a network
Briefly explain a MAC address
When a switch receives a data packet, it reads the MAC address of the destination device and maps it to a port. It then keeps this information in a MAC address table.
Think of the MAC address table like an address book that the switch uses to direct data packets to the appropriate device.
Explain the functions at layer 3 of the OSI model: the Network layer
Functions at the network layer organize the addressing and delivery of data packets across the network from the host device to the destination device.
This includes directing the packets from one router to another router across the internet, till it reaches the internet protocol (IP) address of the destination network. The destination IP address is contained within the header of each data packet. This address will be stored for future routing purposes in routing tables along the packet’s path to its destination.
All data packets include an IP address. A data packet is also referred to as an IP packet for TCP connections or a datagram for UDP connections. A router uses the IP address to route packets from network to network based on information contained in the IP header of a data packet. Header information communicates more than just the address of the destination. It also includes information such as the source IP address, the size of the packet, and which protocol will be used for the data portion of the packet.
What is contained in the Header of a data packet (4)?
- Source IP address
- Size of the packet
- Destination IP address
- Which protocol will be used for the data portion of the packet
What is a data packet referred to for TCP connections?
IP packet
What is a data packet referred to for UDP connections?
Datagram
How many sections are made up in an IPv4 packet?
Two (2)
What are the sections that are made up in an IPv4 packet?
- Header
- Data
Explain the IPv4 header format
An IPv4 header format is determined by the IPv4 protocol and includes the IP routing information that devices use to direct the packet.
The size of the IPv4 header ranges from 20 to 60 bytes.
The first 20 bytes are a fixed set of information containing data such as the source and destination IP address, header length, and total length of the packet.
The last set of bytes can range from 0 to 40 and consists of the options field.
The length of the data section of an IPv4 packet can vary greatly in size.
However, the maximum possible size of an IPv4 packet is 65,535 bytes.
It contains the message being transferred over the internet, like website information or email text.
How many fields are within the header of an IPv4 packet?
Thirteen (13)
What are the fields that are within the header of an IPv4 packet?
- Version (VER)
- IP Header Length (HLEN or IHL)
- Type of Service (ToS)
- Total Length
- Identification
*Flags - Fragmentation Offset
- Time to Live (TTL)
- Protocol
- Header Checksum
- Source IP Address
*Destination IP Address - Options
Define the Version (VER) field within the header of an IPv4 packet
This 4 bit component tells receiving devices what protocol the packet is using.
Define the IP Header Length (HLEN or IHL) field within the header of an IPv4 packet
HLEN (or IHL) is the packet’s header length.
This value indicates where the packet header ends and the data segment begins.
Define the Type of Service (ToS) field within the header of an IPv4 packet
Routers prioritize packets for delivery to maintain quality of service on the network.
The ToS field provides the router with this information.
Define the Total Length field within the header of an IPv4 packet
This field communicates the total length of the entire IP packet, including the header and data.
The maximum size of an IPv4 packet is 65,535 bytes.
Define the Identification field within the header of an IPv4 packet
IPv4 packets can be up to 65,535 bytes, but most networks have a smaller limit. In these cases, the packets are divided, or fragmented, into smaller IP packets.
The identification field provides a unique identifier for all the fragments of the original IP packet so that they can be reassembled once they reach their destination.
Define the Flags field within the header of an IPv4 packet
This field provides the routing device with more information about whether the original packet has been fragmented and if there are more fragments in transit.
Define the Fragmentation Offset field within the header of an IPv4 packet
The fragment offset field tells routing devices where in the original packet the fragment belongs.
Define the Time to Live (TTL) field within the header of an IPv4 packet
TTL prevents data packets from being forwarded by routers indefinitely. It contains a counter that is set by the source. The counter is decremented by one as it passes through each router along its path.
When the TTL counter reaches zero, the router currently holding the packet will discard the packet and return an ICMP Time Exceeded error message to the sender.
Define the Protocol field within the header of an IPv4 packet
The protocol field tells the receiving device which protocol will be used for the data portion of the packet.
Define the Header Checksum field within the header of an IPv4 packet
The header checksum field contains a checksum that can be used to detect corruption of the IP header in transit.
Corrupted packets are discarded.
Define the Source IP Address field within the header of an IPv4 packet
The source IP address is the IPv4 address of the sending device.
Define the Destination IP Address field within the header of an IPv4 packet
The destination IP address is the IPv4 address of the destination device.
Define the Options field within the header of an IPv4 packet
The options field allows for security options to be applied to the packet if the HLEN value is greater than five. The field communicates these options to the routing devices.
How many fields are within the header of an IPv6 packet?
Eight (8)
What are the fields that are within the header of an IPv6 packet?
- Version (VER)
- Traffic Class
- Flow label
- Payload Length
- Next Header
- Hoop Limit
- Source IP Address
- Destination IP Address
IPv4 VS IPV6 Headers
The IPv6 header format is much simpler than IPv4. For example, the IPv4 Header includes the IHL, Identification, and Flags fields, whereas the IPv6 does not. The IPv6 header only introduces the Flow Label field, where the Flow Label identifies a packet as requiring special handling by other IPv6 routers.
There are some important security differences between IPv4 and IPv6. IPv6 offers more efficient routing and eliminates private address collisions that can occur on IPv4 when two devices on the same network are attempting to use the same address.
An Internet Protocol (IP) address is a unique string of characters that identifies the _____ of a device on the internet.
- operating system
- size
- location
- speed
location
Which of the following is an example of an IPv4 address?
- 25, 443, 20
- 172.16.254.1
- 00-B1-D0-63-C2-26
- 2001:0db8:85a3:0000:0000:8a2e:0370:7336
172.16.254.1
An example of an IPv4 address is 172.16.254.1. IPv4 addresses are written as four, 1-3-digit numbers separated by decimal points. Each one can contain the values 0-255.
What type of address is assigned by an internet service provider and connected to a geographic location?
- WAN address
- Public IP address
- MAC address
- Private IP address
Public IP address
A public IP address is assigned by an internet service provider and shared by all devices on a local area network. It is connected to geographic location. All communications from devices in the same local area have the same public-facing address due to network address translation or a forwarding proxy.
A switch uses a MAC _____ to direct data packets to the correct device.
- address table
- geographic location
- home network
- public address
geographic location
A switch uses a MAC address table to direct data packets to the correct device.
