1.4 Introduction to IP Flashcards
N10-009 Obj 1.4 Explain common networking ports, protocols, services, and traffic types (23 cards)
What is the primary function of the Internet Protocol (IP) in networking?
IP is responsible for delivering data packets from the source to the destination across interconnected networks.
It acts like a moving truck that transports data across the network (the roads).
“In this example, this truck is the Internet Protocol… moving that data across the network.” (1:00–1:06)
What role do TCP and UDP play in the transmission of application data over IP networks?
TCP and UDP are transport layer protocols that encapsulate application data for delivery across the network.
They are the boxes inside the truck that hold application data.
“We package that information into a virtual moving box… those boxes as the TCP or UDP protocol.” (1:20–1:43)
What is encapsulation in networking?
The process of wrapping data inside protocol layers, such as TCP inside IP inside Ethernet.
“This process of encapsulating data… is a fundamental process…” (1:50–2:02)
What are the key components of an Ethernet frame?
Ethernet header, Ethernet payload, and Ethernet trailer.
“At the beginning of the frame is an Ethernet header… at the end… Ethernet trailer.” (2:15–2:24)
What are the main headers in a full network frame when transferring web data?
Ethernet header → IP header → TCP header → Application data (e.g., HTTP).
“Ethernet header… IP header… TCP header… website data.” (2:49–3:02)
At what OSI layer do TCP and UDP operate?
OSI Layer 4 – Transport Layer.
“TCP and UDP operate at OSI layer 4, or the transport layer.” (3:37–3:41)
What are the key characteristics of the Transmission Control Protocol (TCP)?
TCP is a connection-oriented protocol that provides reliable delivery through the use of acknowledgments and flow control.
“TCP… connection-oriented… acknowledgment… reliable delivery…” (4:06–4:30)
What is flow control in TCP?
The receiver telling the sender to speed up or slow down data transmission based on its capacity.
“Flow control… the receiving station telling the sending device…” (5:12–5:28)
What are the key characteristics of the User Datagram Protocol (UDP)?
UDP is a connectionless protocol that provides unreliable delivery, with no acknowledgments, no error recovery, and no flow control.
“UDP… no formal process to set up a session… no acknowledgment… unreliable…” (5:33–6:06)
What does it mean that UDP provides unreliable delivery?
It means UDP does not guarantee data delivery because it lacks acknowledgments, error detection, and retransmission mechanisms.
No flow control; sender determines the amount of data sent
“We refer to this type of communication as unreliable… no way to retransmit…” (6:02–6:40)
What does a TCP/UDP socket consist of?
An IP address, a transport protocol (TCP/UDP), and a port number.
“This socket is a combination of data… IP address, a protocol… and an application port number.” (8:18–8:29)
What is the purpose of a port number in IP communication?
To identify the specific application or service on a device (like a room in a house).
“Each box of data is provided a room name… provided via a TCP or UDP port number.” (7:33–7:43)
What is multiplexing in TCP/UDP communication?
The process of sending multiple application streams between two devices simultaneously using different ports.
“This describes the efficient process of transferring multiple applications simultaneously…” (3:55–3:59)
What is a non-ephemeral (well-known) port?
A permanent port number from 0–1023, typically assigned to standard services like HTTP (80).
“Well-known applications… port numbers are from 0 through 1,023… permanent port numbers.” (8:53–9:07)
What is an ephemeral port?
A temporary client-side port number from 1024–65535, used for outbound communication.
“Ports… used on a temporary basis… ephemeral ports… commonly 1,024 through 65,535.” (9:24–9:31)
Can servers use ephemeral port numbers?
Yes, any device can use any port number, although it’s uncommon for servers to use ephemeral ports.
Servers will typically use the well-known ports and clients will use ephemeral ports.
“You could find application servers using port numbers within the ephemeral port range.” (9:52–10:02)
Are TCP and UDP port numbers shared?
No, TCP port 80 and UDP port 80 are separate and can be used by different applications.
“TCP port numbers are different than UDP port numbers… use both at the same time.” (11:28–11:44)
How do servers and clients typically use port numbers in TCP/IP communication?
Servers typically use well-known (non-ephemeral) ports in the range 0–1023 to host services like HTTP (80) or HTTPS (443), while clients use ephemeral ports in the range 1024–65535 to initiate temporary connections.
Transcript (9:02–9:31):
“We refer to these as nonephemeral ports, which means they are permanent port numbers. If we need to communicate to a web server, we’re almost always going to use port 80 and port 443… On the client side, we tend to use port numbers on a temporary basis. And we refer to those as ephemeral ports. Those are ports that are commonly associated with 1,024 through 65,535.”
If a client at IP 10.0.0.1 connects to a web server at 10.0.0.2 on TCP port 80, what might the client port be?
A random ephemeral port, such as 3000.
“Client is using a temporary port… randomized temporary port number is port 3000.” (12:46–12:50)
How does a server respond to a client’s request over TCP?
It reverses the source/destination IPs and source/destination ports to send data back.
“It simply reverses the TCP source port and destination port…” (13:06–13:14)
Can a server run multiple services on different ports simultaneously?
Yes. For example, TCP 80 (HTTP), UDP 5004 (VoIP), and TCP 143 (IMAP) can all be active.
“The server has a web server at TCP port 80… and email on TCP port 143.” (12:09–12:18)
Does changing a port number increase security?
No, port numbers are not a security feature. A firewall is required for traffic filtering.
“This is not a security mechanism… you’ll still need a firewall…” (10:39–10:45)
Why might a web browser fail to connect if the server port is changed from 80/443?
The browser expects those standard ports; if changed, it must be manually reconfigured to match.
“If you change the port numbers of the server, your browser will no longer know how to connect…” (11:03–11:10)
