Module 1 Flashcards
What is the OSI model?
The OSI (Open Systems Interconnection) model is a framework for understanding how communications protocols work. It divides the process of transmitting data over a network into seven layers, each with a specific function.
How many layers does the OSI model have?
The OSI model has seven layers.
What is the function of the Physical layer in the OSI model?
The Physical layer deals with the physical connection between devices, such as cables and switches.
What is the function of the Data Link layer in the OSI model?
The Data Link layer deals with the transmission of data over a physical connection. It is responsible for creating and interpreting packets of data, and providing error checking and correction.
What is the function of the Network layer in the OSI model?
The Network layer deals with the routing of packets between devices. It is responsible for determining the best path for data to take across a network.
What is the function of the Transport layer in the OSI model?
The Transport layer provides end-to-end communication between applications running on different devices. It is responsible for ensuring that data is delivered reliably and in the correct order.
What is the function of the Session layer in the OSI model?
The Session layer establishes, maintains, and terminates connections between applications.
What is the function of the Presentation layer in the OSI model?
The Presentation layer deals with the format of the data being transmitted, such as converting it between different types of encoding.
What is the function of the Application layer in the OSI model?
The Application layer is the top layer, which provides the interface for applications to access the network and send and receive data.
What is the TCP/IP protocol suite?
The TCP/IP (Transmission Control Protocol/Internet Protocol) protocol suite is a set of protocols that are used to transmit data over networks, including the internet. It is the foundation of all internet communication and is based on the four-layer conceptual model (also known as the “Internet Protocol Suite”).
How many layers does the TCP/IP model have?
The TCP/IP model has four layers.
What is the function of the Link Layer in the TCP/IP model?
The Link Layer corresponds to the Data Link layer in the OSI model. It is responsible for establishing and maintaining the physical link between devices, such as through the use of Ethernet.
What is the function of the Internet Layer in the TCP/IP model?
The Internet Layer corresponds to the Network layer in the OSI model. It is responsible for routing packets of data between devices, through the use of the IP (Internet Protocol).
What is the function of the Transport Layer in the TCP/IP model?
The Transport Layer corresponds to the Transport layer in the OSI model. It is responsible for providing end-to-end communication between applications, through the use of the TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
What is the function of the Application Layer in the TCP/IP model?
The Application Layer corresponds to the Application layer in the OSI model. It is responsible for providing interfaces for applications to access the network and send and receive data. Examples of protocols at this layer include HTTP, FTP, DNS, and SMTP.
Is the TCP/IP protocol suite only used on the Internet?
No, the TCP/IP protocol suite is widely adopted as a standard for communication over networks and it’s also commonly used in local area networks (LANs) and wide area networks (WANs).
What is the TCP protocol?
TCP (Transmission Control Protocol) is a transport layer protocol used to establish a reliable, ordered and error-checked channel between two devices for the communication of data. It is one of the core protocols of the Internet Protocol (IP) suite, and is used by many of the most popular internet applications.
How does TCP establish a connection?
TCP is a connection-oriented protocol. When a device wants to establish a connection with another device, it sends a TCP packet called a SYN (synchronize) packet to initiate the connection. The receiving device responds with a SYN-ACK (synchronize-acknowledge) packet to confirm that the connection has been established.
How does TCP exchange data?
Once the connection is established, the devices can exchange data by sending TCP packets, which include a sequence number and an acknowledgement number. The sequence number is used to keep track of the order of the packets, and the acknowledgement number is used to confirm that packets have been received.
How does TCP close a connection?
When the communication is finished, the connection is closed by sending a FIN (finish) packet from one device to the other, which will be acknowledged with an ACK packet.
What is the main advantage of TCP?
TCP is considered a reliable protocol because it guarantees that packets will be delivered to their destination in the correct order and without errors, if any error occurs, it will retransmit the packet.
What is the main disadvantage of TCP?
The main disadvantage of TCP is that it has a higher overhead and it’s slower than the UDP protocol.
What is the UDP protocol?
UDP (User Datagram Protocol) is a transport layer protocol that is used to send data over a network. It is a connectionless protocol, which means that it does not establish a virtual connection before exchanging data.
How does UDP differ from TCP in terms of error checking and retransmission?
Unlike TCP, UDP does not provide any error-checking or retransmission of lost packets. This means that UDP packets may be lost, duplicated or delivered out of order and the sender or receiver have no way to know it. Because of this, UDP is considered an unreliable protocol.
What are the common uses of UDP?
UDP is commonly used for applications that require low latency, such as online gaming, video conferencing, and streaming of multimedia content. Additionally, it’s used for some specific services like Domain Name System (DNS) or Simple Network Management Protocol (SNMP).
What is the structure of a UDP packet?
UDP packets have a very simple structure, they consist of a header and the payload. The header contains the source and destination port numbers, as well as the length of the packet. The payload contains the actual data being sent.
What is the main advantage of UDP?
The main advantage of UDP is that it has lower overhead and it is faster than TCP.
What is the IP protocol?
IP (Internet Protocol) is a network layer protocol that is responsible for routing packets of data across a network. It is one of the core protocols of the Internet Protocol (IP) suite and is used by most devices that connect to the internet.
What is the main function of IP?
The main function of IP is to deliver packets of data, called datagrams, from the source device to the destination device based on the destination IP address.
How is the structure of an IP packet?
IP packets have a simple structure, consisting of a header and a payload. The header contains the source and destination IP addresses, as well as other information such as the time to live (TTL) and the protocol being used at the transport layer. The payload contains the actual data being sent.
How does IP work?
IP is a connectionless protocol, meaning it doesn’t establish a virtual connection before sending data. IP is responsible for routing the packets of data to the right destination.
How does IP route data across networks?
IP is responsible for routing data across networks, even if they are not directly connected. This is done through the use of routers, which forward IP packets based on their destination IP address and the routing tables stored in their memory.
What are the two versions of IP that are widely used today?
IP version 4 (IPv4) and IP version 6 (IPv6) are the two versions of IP that are widely used today. IPv4 addresses are 32-bit and IPv6 addresses are 128-bit, and IPv6 is designed to solve the address exhaustion problem of IPv4.
What is the ARP protocol?
ARP (Address Resolution Protocol) is a protocol that is used to map a network layer protocol address, such as an IP address, to a link layer protocol address, such as a MAC (Media Access Control) address. It is used to find the MAC address of a device on a local area network (LAN) when only its IP address is known.
How does ARP work?
When a device wants to communicate with another device on a LAN, it first needs to determine the MAC address of the destination device. It does this by sending an ARP request packet, which contains the IP address of the destination device. The device with that IP address will then respond with its MAC address in an ARP reply packet.
What is Reverse ARP (RARP)?
Reverse ARP (RARP) is a variation of ARP, it’s used to find the IP address of a device when only its MAC address is known, by sending an ARP request packet with the MAC address and waiting for an ARP reply packet.
Is ARP a stateless protocol?
Yes, ARP is a stateless protocol, which means that it does not maintain a table of previously looked-up addresses. Each ARP request is sent independently, and the information is not stored for future use.
How are ARP requests and replies sent?
ARP request and reply packets are broadcast to all devices on the LAN, but only the device with the matching IP address will respond.
What is the ICMP protocol?
ICMP (Internet Control Message Protocol) is a network layer protocol that is used to send error messages and operational information about network conditions. It is a integral part of the Internet Protocol (IP) suite, and is used by devices to send error messages and operational information about network conditions.
What are the common uses of ICMP?
ICMP messages are typically generated by network devices, such as routers, to indicate error conditions or to provide other information about the status of the network. For example, an ICMP “destination unreachable” message may be sent by a router to inform a sending device that a destination host or network is unreachable. Similarly, ICMP “time exceeded” message may be sent by a router to inform a sending device that a packet has been discarded because it exceeded the maximum time allowed for it to traverse the network.
What is the “ping” message?
One of the most well-known ICMP message is the “ping” message, which is used to test the reachability of a host and to measure the round-trip time for packets to travel from the source host to the destination host and back. A ping packet is a echo request packet, when it reaches the destination host, it sends an echo reply packet back.
How does ICMP differ from other protocols in the IP suite?
ICMP is an integral part of IP, but it has some specific characteristics, it is unreliable and it’s not connection-oriented, so it can’t guarantee that the message will be delivered or in what order.
What is the main use of ICMP?
In summary, ICMP is a network protocol that is used to send error messages and operational information about network conditions, and it’s widely used to diagnose and troubleshoot network issues.
What is the structure of a TCP datagram?
The structure of a TCP datagram includes several fields that are used for various purposes such as identifying the sender and receiver, controlling the flow of data, and ensuring data integrity.
Q: What is the purpose of the source port field in a TCP datagram?
A: The source port field is a 16-bit field that identifies the sender’s port number.
Q: What is the purpose of the sequence number field in a TCP datagram?
A: The sequence number field is a 32-bit field that is used to keep track of the order of the packets.
Q: What is the purpose of the control bits field in a TCP datagram?
A: The control bits field is a 6-bit field that contains various control flags such as SYN, FIN, ACK, and RST.
Q: What is the purpose of the window size field in a TCP datagram?
A: The window size field is a 16-bit field that indicates the number of bytes that the sender is willing to receive.
Q: What is the purpose of the checksum field in a TCP datagram?
A: The checksum field is a 16-bit field that is used to ensure data integrity by detecting errors in the packet.
Q: What is the purpose of the options field in a TCP datagram?
A: The options field is a variable-length field that can be used to include additional information such as the maximum segment size and timestamps.
Q: What is the structure of a UDP datagram?
A: The structure of a UDP datagram is simpler than that of a TCP datagram, as it is a connectionless, unreliable protocol. It includes fields for source and destination port numbers, length and checksum.
Q: What is the purpose of the source port field in a UDP datagram?
A: The source port field is a 16-bit field that identifies the sender’s port number.
Q: What is the purpose of the destination port field in a UDP datagram?
A: The destination port field is a 16-bit field that identifies the receiver’s port number.
Q: What is the purpose of the length field in a UDP datagram?
A: The length field is a 16-bit field that indicates the total length of the UDP datagram, including the header and data.
Q: What is the purpose of the checksum field in a UDP datagram?
A: The checksum field is a 16-bit field that is used to detect errors in the packet.
Q: Is the checksum field mandatory in UDP?
A: The checksum field is optional in UDP, if it’s not used, the value in this field is set to zero.
Q: What is the structure of an IP packet?
A: The structure of an IP packet includes several fields that are used for various purposes such as identifying the sender and receiver, controlling the flow of data, and ensuring data integrity.
Q: What is the purpose of the version field in an IP packet?
A: The version field is a 4-bit field that indicates the version of IP being used (4 for IPv4 and 6 for IPv6).
Q: What is the purpose of the Type of Service (ToS) field in an IP packet?
A: The Type of Service (ToS) field is an 8-bit field that is used to indicate the quality of service (QoS) desired for the packet.
Q: What is the purpose of the Time To Live (TTL) field in an IP packet?
A: The Time To Live (TTL) field is an 8-bit field that is used to indicate the maximum number of hops a packet can traverse before being discarded.
Q: What is the purpose of the Protocol field in an IP packet?
The Protocol field in an IP packet is an 8-bit field that indicates the type of transport layer protocol being used (e.g. TCP, UDP, ICMP) in the packet.
Q: What is the structure of an Ethernet frame?
A: The structure of an Ethernet frame includes several fields that are used for various purposes such as identifying the sender and receiver, controlling the flow of data, and ensuring data integrity.
Q: What is the purpose of the destination MAC address field in an Ethernet frame?
A: The destination MAC address field is a 48-bit field that contains the MAC address of the intended recipient of the frame.
Q: What is the purpose of the source MAC address field in an Ethernet frame?
A: The source MAC address field is a 48-bit field that contains the MAC address of the sender.
Q: What is the purpose of the EtherType field in an Ethernet frame?
A: The EtherType field is a 16-bit field that indicates the type of payload that is included in the frame (e.g. IP, ARP, VLAN).