Networking Flashcards
Where is the HTTP protocol used?
Worldwide Web
What is the SMTP protocol used for?
Sending/receiving emails
What is the FTP protocol used for?
File transfers over a network
What is the SMB protocol used for?
Shared folder access over a network
What are port numbers used for?
Since applications do not have direct access to network hardware, the OS will help service the network requests.
The OS assigns each request from an application with a random (source) port number, so that the response can be passed back to the correct application.
What does 127.0.0.1 refer to?
loopback network interface/localhost
What is packet forwarding?
It is the process by which data is sent from computer to computer until it reaches its destination. (internet layer)
What is the name of the packet forwarding model used by the TCP and UDP protocols?
Unicasting, whereby data is forwarded from server to server, until it reaches its destination. (transport layer)
How does unicast packet forwarding work?
(internet)
Each computer on the network is connected to a gateway.
When an application needs to send data to a destination (IP address), the computer checks all other computers connected to it to see if the destination is listed there.
If not, the data is forwarded to the computer’s gateway.
At the gateway, the process is repeated.
If the destination is not in the list of computers in the gateway, the data is forwarded to the next gateway and checked again until the destination is found and the packet is sent to the destination.
What are the steps involved in DNS lookup?
(application)
1. DNS client checks its DNS cache for DNS entries containing the domain name. If one is found, the corresponding IP address is used. Otherwise …
2. DNS client sends a DNS lookup request to a (recursive) DNS resolver.
3. DNS resolver checks its own DNS records for the domain name. If DNS record is found, DNS server returns response with the requested IP address. Otherwise, it sends the request to a DNS root server.
3. The root server sends the address of the authoritative (TLD) DNS server request to the resolver.
4. The resolver queries the authoritative DNS server for the IP address.
5. The resolver sends the IP address back to the client.
What is the DNS cache?
It is a location where the computer stores the IP addresses returned for the domains. This is done so that next time a DNS lookup is requested, the computer checks in the DNS cache first, to minimize requests to the DNS server.
The DNS cache may need to be flushed if it gets outdated.
What do top level domains (TLDs) refer to?
Suffixes such as .gov, .edu and .com.
What is a protocol?
It is a set of rules for communication agreed upon by both the sender and receive to define how data is transmitted
- this is to ensure data is correctly transmitted as communication over a network is often unreliable and maybe intercepted and dropped
What is a protocol suite?
It is a collection of related protocols that are designed to work together.
What is the IP protocol? What is its purpose?
It forms the Internet layer of the TCP/IP model. Its purpose is to identify computers on the Internet.
- this include information that ensure the data packet is sent to the correct destination
This allows packet routing to be used for the Internet.
What is client-server architecture?
A client is a device or program that sends a request to a server.
The server returns a response to the client.
What is a request?
A request is data sent by a client to a server.
What is a response?
The server sends a response (containing data) to the client when a client sends a request to the server.
What are the 4 layers of the TCP/IP protocol stack?
- Application Layer
- Transport Layer
- Internet Layer
- Network Layer
What is a circuit-switched network?
In a circuit-switched network:
1. A dedicated communication path is established between source and destination.
2. Each part of the data transmission stream follows the same route to its destination
3. The returning data stream follows the same route back to the source
What is a packet-switched network?
In a packet-switched network:
1. There is no dedicated transmission capacity along a path: each packet may go by a different route to its destination
2. The data to be sent is broken up into packets
3. Each packet may go by a different route to its destination
4. packet headers determines the destination and method of transmission
advantages of circuit switched network
- the path of transmission has a guaranteed bandwidth
-2. since information is sent in a continuous stream, the intermediate nodes do not need to store and retransmit information = LOWER OVERHEAD
disadvantages of circuit switched network
- both sender and receiver need to be ready for the transmission to happen
- if transmission route is disrupted, the WHOLE transmission is interrupted
- unused segments cannot be used to divert data transmission = LOW UTLISATION
disadvantages of packet-switched network
- packets may arrive in different sequence, hence sequence information must be sent with the packet header
- packet data must be stored and retransmitted at each node, making it more prone to data corruption - additional bits for error detection and correction must be sent
- BOTH WILL RESULT IN GREATER OVERHEAD INCURRED - intermediate nodes need to store and retransmit data (greater overhead incurred)
