Computing - TCP & IP Stack
What is the TCP/IP stack?
A set of rules to format a message so it can be sent over a network.
What are the four layers in networking?
- Applicatoin
- Transport
- Internet
- Link
What does ATIL stand for in networking?
- Application
- Transport
- Internet
- Link
What does each layer do in the TCP/IP stack?
Wraps a packet with header data.
What is the Application layer used for?
Providing services for applications that want to communicate across a network.
Instead of determing how the data will be sent, what does the Application layer do?
Specifies rules of what should be sent.
What is an example of Application layer protocols?
- HTTP
- HTTPS
- SMPT
- FTP
What is the Transport layer used for?
Establishing an end-to-end connection with a recipient computer.
What procotol does the Transport layer use?
TCP.
What does TCP do to data in order to send it over the network?
Splits it into packets and numbers them sequentially.
At the recieving end of the TCP protocol, what will the client do?
Confirms the packets have been recieved and requests any missing packets.
What protocol does the Network layer use?
IP.
What is a socket?
A combination of an IP address and a port number.
Why does a router send a packet to a socket rather than an IP address?
Because the socket contains both the IP address and the port number.
What does the IP do to packets?
Adds source and destination IP addresses.
What is the Link layer used for?
Sending packets across a physical connection.
What does the Link layer add to packets?
The MAC address of the destination.
What does the Link layer on the recieving end do to each packet?
Removes the MAC address and passes it to the Network layer.
What does the Network layer on the recieving end do to each packet?
Removes the IP address from each packet and passes it to the Transport layer.
What 2 things does the Transport layer on the recieving end do to each packet?
Removes the port number from each packet and reassembles the packets in the correct order before passing it to the Application layer.
What is a MAC addresses?
A code that uniquely identifies a physical NIC.
What does this diagram show?
What does this diagram show?SSH tunnelling.
What is SSH tunnelling used for?
Securely passing data through a network that might otherwise be blocked.
What is SMTP used for?
Sending emails.
What is POP3?
An old email protocol that removed emails from the server after they’d been seen.
What is IMAP used for?
Recieving emails.
2021-02-23
What is an IP addresses?
A unique identifier given to a computer or network node.
What does a $x.y.z.0$ IP address represent?
The gateway to the network, such as the router.
What does a $x.y.z.255$ IP address represent?
A broadcast address that will send data simultaneously to all hosts on a network.
What does a $127.x.y.z$ IP address represent?
Loopback
What is a loopback address?
Where outgoing data sent to that address is treated as incoming.
How many devices can be on a $54.12.89.x$ network?
How many bits in an IPv6 address?
How many chunks of 4 hexadecimal characters are there in an IPv6 address?
What are the two parts of an IP address?
- A network identifier
- A host identifier
What is the difference between an network identifier and a host identifier in an IP address?
Network identifiers identify the network as a whole, host identifiers identify a specific device on a network.
\[142.67.57.253\]
What is the network ID of this IP address?
\[142.67.57.253\]
What is the host ID of this IP address?
What are the two types of IP addressing (not versions)?
- Classful
- Classless
What does $210.54.101.0/24$ mean?
An IP address that has 24 bits of a network ID.
Is $210.54.101.0/24$ classless or classful addressing?
Classless.
Why do we use classless suffixes like $/24$ in IP addresses?
Because it enables IP addresses with varying proportions of Network IDs and Host IDs.
How does a computer know what is the Network ID when using classless addressing?
It uses a subnet mask.
How does a subnet mask work?
It has all Network ID bits set to $1$ so that when it is ANDed with the IP it leaves only the Network ID.
If a network has a subnet mask $11111111.11111111.11111111.11110000$, how many hosts can operate on the network?
Why might an organisation want to use subnetting?
- It reduces the broadcast domain
- It reduces data collisions
- It improves security
What is subnetting?
Where an organisation decides to further subdivide the number of host IDs within a network in order to create individual subnetworks.
2020-03-03
What does DHCP stand for?
Dynamic Host Configuration Protocol.
What is the purpose of DHCP?
To provide a host with an IP address and other information on a network.
What examples of information does DHCP provide?
- IP address
- Subnet mask
- Default gateway