Networking Flashcards

What is the purpose of the network model?

To standardize processes at each layer

What are some limitations of network models?

They are theoretical and a protocol may not necessarily represent every layer

What two methods help detect lost packets?

Acknowledgements and sequencing

What corporation regulates port usage?

ICANN (Internet Corporation for Assigning Names and Numbers)

What is the range of registered ports?

1024 - 49151

What identifies a service running on a server?

Port or socket numbers

Layers of the OSI model

Application, Presentation, Session, Transport, Network, Data Link, Physical

Layers of the TCP/IP model

Application, Transport, Internet, Link

What port is DHCP (Dynamic Host Configuration Protocol) on?

UDP ports 67 and 68

What port is NNTP (Network News Transport Protocol) on?

TCP port 119

What port is SNMP (Simple Network Management Protocol) on?

UDP ports 161 and 162

What port is DNS (Domain Name System) on?

TCP and UDP port 53

What port is Telnet on?

TCP and UDP port 23

What port is TFTP (Trivil File Transfer Protocol) on?

UDP port 69

How does TCP handle data sequencing?

It breaks data into segments, numbers each segment, places them in a sequence, sends each one in order, waiting for an acknowledgement before continuing to the next segment

What is the difference between TCP and UDP?

TCP is more reliable but slower/resource heavy, UDP is quicker and lighter but does not use acknowledgements

What is used to keep two concurrent downloads seperate?

Session ID

What does the MAC sublayer do in the OSI model?

Defines unique hardware addresses for each device and allows devices to have access to LAN

What is used to get the IP address of a host from a known MAC address?

BOOTP (Bootstrap Protocol) and RARP (Reverse Address Resolution Protocol)

Used to transfer files

FTP and TFTP

Used to identify routes through an internetwork.

Open Shortest Path First (OSPF) and Routing Information Protocol (RIP)

What does the application layer do?

Prepares data to be sent through the network

The transport layer breaks data into…

segments, adding sequencing and control information

The network layer converts segments into…

packets, adding logical network and device addresses

The data link layer converts packets into…

frames, adding physical device addressing information

The physical layer converts the frames into…

bits, for transmission across transmission media

What OSI layer does this: Logical topology, hardware addresses, media access, framing

Data Link

What OSI model layer does this: Logical device identification, path identification, and selection

Transport

What OSI model layer does this: Flow control, reliable data transfer, windowing, segmentation, and sequencing

Transport

What OSI model layer does this: Converting data to 0s and 1s, bit signaling, and synchronization

Physical

What does CRC (Cyclical Redundancy Check) do in network communications?

Detects data errors

What sends email messages between mail servers?

Simple Mail Transfer Protocol (SMTP)

What sends messages to groups of users?

Internet Group Membership Protocol (IGMP)

What assigns IP addresses to hosts?

The Dynamic Host Configuration Protocol (DHCP)

What is used to get the MAC address of a host from its IP

The Address Resolution Protocol (ARP)

What functions are performed by IP?

Routing datagrams to their destination and identifying hosts with the IP address

You want to implement an Ethernet network using the 100Base-FX standard and the minimum hardware specifications possible. You need to support distances of up to 1,000 meters without repeaters.

SC connectors, Single-mode fiber optic cable

What characteristics does each fiber optic connector have: ST, SC, LC, MT-RJ

ST uses a bayonet-type connector

SC uses a separate push-on, pull-off connector

LC is half the size of other connectors

MT-RJ connector uses metal guide pins

What are features of multimode fiber cables?

They support limited distance cable lengths, have a core diameter of around 50-100 microns, and transfer data through the core with multiple light rays

What are features of single-mode fiber cables?

Transfers data through core with a single light ray, supports large amounts of data, core diameter of around 10 microns, supports large cable distance

When should you use a straight-through cable?

When connecting different network devices, such as a computer and switch

When should you use a crossover cable?

When connecting similar network devices directly, such as computer to computer or switch to switch

Determine whether each connection should use a straight-through or crossover cable.

A: straight-through (two different devices)

B: crossover (hub and switch are similar)

C: straight-through (two different devices)

E: crossover (two switches connected)

F: straight-through (two different devices)

G: crossover (PC is directly connected to router)

What is true about CAT 6 cabling?

It supports 10 GB ethernet connections, has a PVC insulation that surrounds each copper wire

What pins are used in Cat 5 ethernet UTP cable?

1, 2, 3, and 6. For Cat 5e and above, all eight pins are used.

You want to implement an Ethernet network using the 1000BaseT standard using the minimum hardware specifications possible. Which of the following should you include in your plan?

Cat5e twisted pair cable, RJ-45 connectors

Which fiber optic cable requires the exposed fiber tip to be polished as part of the assembly process?

Field terminated epoxy connectors

What connectors do fiber optic cables use?

LC, ST, or SC connectors. 100BaseFX, 1000BaseSX, and 1000BaseLX are all standards that use fiber optic.

What does RP (Address Resolution Protocol) do?

If a router does not know a destination device’s MAC address, it sends an ARP broadcast containing the destination device’s IP address and requesting its MAC address

What TCP/IP layer breaks data into pieces?

Transport

What TCP/IP layer prepares data to be sent?

Application

Which TCP/IP layer adds physical addresses?

Link

Which TCP/IP layer adds logical addresses?

Internet

What is the purpose of the frame check sequence (FCS) footer?

Checksum error detection

What does the OSI model call frames, packets, and segments?

Protocol data unit (PDU)

Workstation2 needs to send data to Workstation3. Identify the Layer 2 and Layer 3 addresses Workstation2 will use to send the data

The source Layer 2 address is its own MAC address, 080046987654.

The source Layer 3 address is its own IP address, 192.168.10.12.

The destination Layer 2 address is the MAC address of the default gateway router, 000b5f2a2222. The MAC address is the address of the interface connected to the same subnet as Workstation2.

The destination Layer 3 address is the IP address of the destination device (Workstation3), 192.168.11.11.

The process of breaking a message into packets, adding control information and other information, and then transmitting the message through the transmission medium is known as…

Encapsulation

Workstation3 has started communicating with Workstation2. It sends a frame to the default gateway. Identify the Layer 2 and Layer 3 addresses used by the Cisco 2600 router to forward the data to Workstation2

The Cisco 2600 router is the default gateway. When it receives a frame from Workstation3, it examines the Layer 3 address in the packet to locate the destination device. Then it creates a new frame and modifies the source and destination Layer 2 addresses (MAC addresses) as follows:

The source Layer 2 address is its own MAC address on the same segment as the destination device, 000b5f2a222.

The destination Layer 2 address is the MAC address of the destination device, 080046987654.

The source and destination Layer 3 addresses (IP addresses) do not change.

The source IP address is the IP address of Workstation3 is 192.168.11.11.

The destination IP address is the IP address of Workstation2 is 192.168.10.12.

What are features of full-duplex ethernet?

collision-free, uses direct point-to-point connections

What is the backoff on an Ethernet network?

The random amount of time a device waits before retransmitting after a collision.

What is true of CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

If collisions are detected, an interrupt jam signal is broadcast to stop all transmissions, A device with data to send first listens to the transmission medium to determine whether it is free.

What is true of Gigabit Ethernet?

It uses CSMA/CD and can use both copper and fiber optic cabling

What is the maximum number of hosts supported on a subnet?

1024

The ethernet frame component that is a set of ones and zeroes terminated by two ones.

Preamble

The ethernet frame component that is information that needs to be transmitted between hosts

Packet

Ethernet frame component that verifies that the data arrived uncorrupted

Frame Check Sequence

Ethernet frame component that identifies the receiving host’s MAC address

Destination address

Ethernet frame component that is junk data required to make 64 bytes

Pad

Ethernet frame component that identifies the sending host’s MAC address

Source address

Ethernet frame component that specifies the network/internet layer protocol being used

Type

What is true of half-duplex ethernet?

It uses collision detection and recovery, and sends both signals along the same wire

What is the maximum cable length for UTP Ethernet T implementations?

100 meters

What do bridges do?

They connect two network segments with the same network address and convert one type of transmission medium into another

What is the function of a dedicated wireless access point on a network?

It acts as a bridge between the wireless and wired segments on the same subnet

Why is DNS important?

It translated human-readable domain names into IP addresses

What are the advantages of using routers on a network?

Routers provide multiple links between devices to support load balancing, they provide feature like flow control, error detection, congestion control, etc. and support multiple routing protocols for better flexibility

You have been put in charge of connecting two company networks that were previously separated.

You need to connect a 100BaseTx Ethernet network with an older token ring network. Most traffic will be localized within each network, with only a little traffic crossing between networks. Both networks are using the TCP/IP protocol suite.

Which connectivity device would be the best choice in this situation?

Router. Both networks use a different architecture but are using the same protocol.

What does DHCP (Dynamic Host Configuration Protocol) do?

Automatically assigns IP addresses to devices

What layer of the OSI model do network switches operate that do not support routing?

Data Link. Multi-layer switches operate at higher layers than this.

What is the difference between Telnet and SSH?

SSH provides encrypted communication while Telnet transmits data in plaintext. Having both enabled could undermine the security of Telnet.

You are troubleshooting a network switch that has lost remote connectivity due to a misconfiguration. Remote access methods such as SSH and HTTPS are no longer functional.

Which of the following actions should you take to regain access to the switch and resolve the issue?

Connect a console cable to the switch and access it through a terminal application on your computer.

What memory type stores the running-config gile, routing tables, and ARP tables?

RAM

What memory type stores the startup-config file?

NVRAM

What memory type stores the Cisco IOS software?

FLASH

What memory type stores POST and the boot loader software?

ROM

You have issued the following command and received the response as shown.

Router#sh start

%%Non-volatile configuration memory has not been set up or has bad checksum

Which of the following is a reason for this response?

No config file has been saved to NVRAM.

If you need to use Telnet on a legacy router, how could you make it more secure?

Use Telnet over a secure VPN connection.

What are the necessary components to make a console connection from PC to router?

Rollover cable, console port, and terminal emulation program

What should you do to properly implement HTTPS on a wireless controller that supports both HTTP and HTTPS?

Install a valid SSL/TLS certificate on the wireless controller and disable HTTP access. HTTPS relies on SSL/TLS encryption to secure communication.

What cable do you use to connect a laptop to a router for troubleshooting?

Rollover cable

What should you do to secure access to a router?

Keep the router in a locked room, set a password and use the login command.

What is the order of events during the boot sequence?

Power-on self-test checks hardware, boot loader software is loaded, IOS is loaded, and the startup-config is loaded.

What command should you use to save the NVRAM config file to a TFTP server?

copy start tftp

Which command would you use to remove the contents of NVRAM?

erase nvram

What command do you use to see the previous list of commands stored in the history buffer on a cisco device?

show history

What should you use to view a list of commands available in the current mode on a cisco device?

?

What command should you use to save the current config to NVRAM?

copy run start

What command should you use to load the current configuration saved in NVRAM into memory?

copy start run

What command saves the current config to a network server?

copy run tftp

What command copies a config file from a network server into NVRAM?

copy tftp start