Networking Models and Protocols Flashcards

A network technician is troubleshooting an issue where a user can ping a web server by its IP address but cannot browse the website using its domain name. Other users on the same network are not experiencing this issue. Which of the following protocols is most likely the cause of this specific user's problem?

Answer: DNS (Domain Name System)

The Domain Name System (DNS) is responsible for translating human-readable domain names (like www.google.com) into machine-readable IP addresses. Since the user can reach the server via its IP address, TCP/IP connectivity is working. The failure to connect using the domain name points to a problem with DNS resolution on that specific user's machine.

Which of the following scenarios is best suited for using the User Datagram Protocol (UDP) instead of the Transmission Control Protocol (TCP)?

Answer: Streaming a live video conference.

UDP is a connectionless protocol that prioritizes speed and low overhead over reliability. It does not guarantee delivery or order of packets. This makes it ideal for real-time applications like video streaming or online gaming, where a few lost packets are preferable to the delay caused by retransmissions that TCP would enforce.

A technician is using the OSI model to troubleshoot a network outage. After verifying that the network cables are properly connected and the link lights on the switch are active, they move to the next layer. At which layer of the OSI model are they now troubleshooting, and what technology operates at this layer?

Answer: Layer 2 (Data Link Layer), Switches and MAC Addresses

The technician has confirmed the Physical Layer (Layer 1) is functional by checking cables and link lights. The next layer in the OSI model is the Data Link Layer (Layer 2). This layer is responsible for node-to-node data transfer and manages how data is placed on and retrieved from the physical media. Switches and MAC addresses are key components that operate at Layer 2.

In the TCP/IP model, which layer is responsible for logical addressing, routing, and path determination for data packets across different networks?

Answer: Internet Layer

The Internet Layer in the TCP/IP model, which corresponds to the Network Layer (Layer 3) of the OSI model, is responsible for these functions. It uses protocols like the Internet Protocol (IP) to assign logical addresses (IP addresses) to devices and to route packets from a source network to a destination network.

Which layer of the OSI model is responsible for establishing, managing, and terminating connections between applications on different hosts?

Answer: Session Layer

The Session Layer (Layer 5) is responsible for creating and managing dialogues, or sessions, between applications. It handles session setup, data exchange, and tear-down when the session is complete.

A user reports that they are unable to access any external websites. A technician runs the `ipconfig` command on the user's computer and finds that the IP address is 169.254.10.22. What protocol has failed to operate correctly?

Answer: DHCP (Dynamic Host Configuration Protocol)

An IP address in the 169.254.x.x range indicates an Automatic Private IP Addressing (APIPA) address. This address is self-assigned by the operating system when a device is configured to obtain an IP address automatically but cannot contact a DHCP server. Therefore, the failure is with the DHCP protocol, which is responsible for automatically assigning IP addresses to devices on a network.