Practice (8) Flashcards
Some networks are designed with a switching fabric that contains redundant paths, for fault tolerance purposes. However, in this type of design, it is possible for packets to circulate endlessly around the network, which is called a switching loop. Which of the following protocols prevents network switching loops from occurring by shutting down redundant links until they are needed?
NAT
RIP
STP
STP
The Spanning Tree Protocol (STP) prevents packets from endlessly looping from switch to switch due to redundant links. Creating redundant links is a good preventive measure against switch failure, but packets transmitted over multiple links can circulate from switch to switch infinitely. STP creates a database of switching links and shuts down the redundant ones until they are needed. None of the other three protocols listed can perform this function. Network address translation (NAT) is a routing method that enables private networks to share registered IP addresses. Routing Information Protocol (RIP) propagates routing table information. A virtual local area network (VLAN) is an organizational tool that operates within switches by creating multiple broadcast domains
You are responsible for an internetwork that consists of four internal local area networks (LANs) with 50 users each. Each internal LAN uses twisted pair Gigabit Ethernet links that connect the users to a switch. Each of the four switches is connected to a separate router. All four routers connect to the same backbone network, which has a single additional router to connect the company’s network to the Internet, using a T-1 wide area network (WAN) link. Today, users on one of the four internal LANs are reporting that when they came in this morning they could not access the Internet or resources on the other three internal LANs. However, they could access resources on their own LAN with no problems. Which network component is the likeliest source of the problem in this scenario?
The switch on the problem LAN
The Internet router
The router connecting the problem LAN to the backbone
The router connecting the problem LAN to the backbone
In this scenario, only users on one LAN are experiencing problems connecting to the Internet and the other internal LANs. This isolates the problem to a component within that LAN only. Since users can connect successfully to local resources, the problem doesn’t lie within the individual computers, the switch that connects the users to the network, or the backbone network cable. The likeliest problem is therefore in the router connecting the problem LAN to the backbone network. Since users on the other internal LANs are not reporting problems connecting to the Internet, the problem most likely does not involve the Internet router
You are negotiating an agreement with a provider for your company’s email service. You have been told to require a 99.99 percent guaranteed rate of service reliability, but the provider is only willing to guarantee 99 percent. Eventually, you and the provider agree on a compromise of 99.9 percent. Which of the following documents will include the negotiated language on this particular point?
AUP
SLA
BYOD
SLA
The agreed upon 99.9 percent guaranteed availability will be part of a service level agreement (SLA), which is a contract between a provider and a subscriber that specifies the percentage of time that the contracted services are available. None of the other three options contain the guaranteed reliability language. Acceptable use policies (AUP) specify whether and how employees can use company-owned hardware and software resources. A nondisclosure agreement (NDA) specifies what company information employees are permitted to discuss outside the company. A Bring Your Own Device (BYOD) policy specifies the personal electronics that employees are permitted to use on the company network and documents the procedures for connecting and securing them
Which of the following types of networking devices can split a single network into multiple collision domains while maintaining a single broadcast domain? (Choose all correct answers.)
Switch
Bridge
Router
Hub
Switch
Bridge
A bridge can split a single network into two collision domains, because it forwards only the packets that are destined for the other side of the bridge. A switch creates a separate collision domain for each port. Both bridges and switches forward all broadcast packets, so they maintain a single broadcast domain for the entire network. A hub maintains a single collision domain and a single broadcast domain. A router creates two collision domains, but it does not forward broadcasts, so it creates two broadcast domains as well
You have just finished installing a web server farm on your company’s network, along with a router to create a perimeter network on which the web servers are located. However, you now cannot access the web servers from your workstation on the internal network. Which of the following is not one of the tasks you will have to complete before you can access the perimeter network from the internal network?
Change MAC addresses
Change IP addresses
Update the DNS records
Change MAC addresses
MAC addresses are hard-coded into network interface adapters and are not easily changeable. There is also no need to change them for this purpose. First, you will have to change IP addresses of the web servers. This is because the computers on the other side of the router, on the perimeter network, must use a IP network address that is different from the internal network’s address. Next, you will have to change the default gateway address setting on the internal network computers to the address of the router on the internal network so that traffic can be forwarded to the perimeter network. Finally, you will have to update the resource records on your DNS server to reflect the IP address changes
You are testing a twisted pair cable run using a tone generator and locator. When you apply the tone generator to a particular pin at one end of the cable, you detect a tone on two pins at the other end. Which of the following faults have you discovered?
Split pair
Open
Short
Short
A short is when a wire is connected to two or more pins at one end of the cable or when the conductors of two or more wires are touching inside the cable. This would cause a tone applied to a single pin at one end to be heard on multiple pins at the other end. The other three options would not cause this to happen. An open circuit would manifest as a failure to detect a tone on a wire, indicating that there is either a break in the wire somewhere inside the cable or a bad connection with the pin in one or both connectors. A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Crosstalk is a type of interference caused by signals on one wire bleeding over to other wires
Your network has been experiencing intermittent service slowdowns and outages ever since the company moved into their new building. You have tried every troubleshooting modality you can think of, but you haven’t been able to determine the cause. One particular user, perhaps hoping to be the squeaky wheel that gets the grease, has taken to calling you every time he experiences a problem. One day, as you are working in the datacenter, you notice that the user calls every time you hear an additional humming noise. After examining the doors in the hallway, you realize that the racks containing the network switches are located right next to the elevator machinery room. Which of the following conditions is probably causing this intermittent network communication problem?
Bottleneck
EMI
Latency
EMI
Elevator machinery, fluorescent light fixtures, and other electrical devices in an office environment can generate magnetic fields, resulting in electromagnetic interference (EMI). When copper-based cables are located too near to such a device, the magnetic fields can generate an electric current on the cable that interferes with the signals exchanged by network devices. If the network users experience a problem every time the elevator machinery switches on, EMI is a likely cause of the problem. Crosstalk and attenuation can both cause intermittent network communication problems, but they cannot be caused by elevator machinery. Latency describes a generalized delay in network transmissions, not intermittent packet delays
A thin Ethernet network uses coaxial cable to connect computers together using a bus topology. Which of the following combinations of attributes describes the type of coaxial cable used for a Thin Ethernet network?
RG-8, 50-ohm, 0.405-inch coaxial cable with N connectors
RG-58, 50-ohm, 0.195-inch coaxial cable with BNC connectors
RG-59, 75-ohm, 0.242-inch coaxial cable with F connectors
RJ45, 50-ohm, 0.270-inch coaxial cable with BNC connectors
RJ6, 75-ohm, 0.242-inch coaxial cable with BNC connectors
RG-58, 50-ohm, 0.195-inch coaxial cable with BNC connectors
Thin Ethernet networks use a type of 50-ohm coaxial cable called RG-58, which is 0.195 inches in diameter and uses Bayonet-Neill-Concelman (BNC) connectors. A 75-ohm coaxial cable with F connectors is used for cable television networks, and RG-8 coaxial is the cable that Thick Ethernet networks use. RJ45 is a type of connector used with twisted pair cables
You are starting work at a new company, and on your first day, you ask about wireless access for your laptop. You are given an SSID and a WPA2 passphrase. Later, in the lunch room, when you try to connect your laptop to the network, you cannot see the SSID you were given in the list of available networks, although you can see other networks. What should you do next to try to resolve the problem?
Move closer to the wireless access point.
Type in the WPA2 passphrase.
Type the SSID in manually.
Type the SSID in manually.
It is possible that the wireless access point has been configured not to broadcast the network’s SSID as a security measure, so you should first attempt to access it by typing the SSID in manually. You cannot type in the WPA2 passphrase until you are in the process of connecting to the SSID. Moving the laptop closer to the access point or away from possible sources of electromagnetic interference might be solutions to the problem, but they should not be the first thing you try in this case
You are responsible for a wireless LAN that consists of an 802.11n 2x2 access point and laptop computers with a variety of network adapters. Some of the laptops support 802.11n, most support 802.11g, and a few older models have 802.11b adapters. The wireless LAN is located in a large office building with many other wireless networks, and you are having trouble finding a channel on the 2.4 GHz band that is not congested with traffic. Scanning the 5 GHz band, you find relatively little traffic, so you reconfigure the access point to use a 5 GHz channel. The result is that some of the laptops are able to connect to the network, whereas others are not. What is the most likely reason for the connection failures, and what must you do to enable all the laptops to connect to the wireless network?
The 802.11b standard does not support communication using the 5 GHz band. You must replace the network adapters in those laptops with newer models for them to connect successfully.
The 5 GHz band does not support automatic channel selection. You must configure each laptop to use the same channel as the access point for all the laptops to connect successfully.
The 802.11g and 802.11b standards do not support communication using the 5 GHz band. You must configure the access point to support 2.4 GHz for all the laptops to connect successfully.
The 802.11g and 802.11b standards do not support communication using the 5 GHz band. You must configure the access point to support 2.4 GHz for all the laptops to connect successfully.
The 802.11b and 802.11g standards do not support 5 GHz communications. Configuring the access point to support 2.4 GHz is the only way for the 802.11b and 802.11g computers to connect to the network. The 5 GHz band does support automatic channel selection, so there is no need to configure the channel on each laptop manually. The 5 GHz band does support MIMO, and the 802.11n laptops should be able to connect. The 802.11b standard does support the 2.4 GHz band
In the Domain Name System (DNS), a zone is a contiguous area of the DNS namespace for which authority is delegated to one or more DNS servers. Which of the following DNS resource record types specifies the IP addresses of the authoritative DNS servers for a particular zone?
PTR
MX
NS
NS
The Name Server (NS) resource record identifies the authoritative servers for a particular DNS zone. Pointer (PTR) resource records are used to resolve IP addresses into hostnames. Mail Exchange (MX) records identify the mail servers for a particular domain. Service Locator (SRV) records identify the designated servers for a particular application. None of these other options identify authoritative servers for a zone
You are experiencing poor performance on your home 802.11n wireless network. You live in a large apartment complex, and when you run a Wi-Fi analyzer, you see many other nearby networks using the often-recommended channels 1, 6, and 11 on the 2.4 GHz frequency. Using the 5 GHz frequency is not an option for your equipment. What should you do to improve the network’s performance?
Configure your equipment to use channel 10.
Configure your equipment to use channel 9.
Configure your equipment to use channel 5.
Configure your equipment to use channel 9.
The 2.4 GHz band used by wireless LANs (WLANs) consists of channels that are 20 (or 22) MHz wide. However, the channels are only 5 MHz apart, so there is channel overlap that can result in interference. Channels 1, 6, and 11 are the only channels that are far enough apart from each other to avoid any overlap with the adjacent channels. This is why they are often recommended. However, in this scenario, these channels are too crowded with other networks. You should therefore use a channel that is as far as possible from the crowded ones. Channels 2, 5, and 10 are all immediately adjacent to a crowded channel, but channel 9 is at least two channels away from the nearest crowded channel. Therefore, you should configure your equipment to use channel 9
Your company’s office building is having a fire inspection, and you are the only person on duty in the datacenter. The inspector from the fire department asks you where they can find documentation about all chemicals and equipment used in the company’s datacenter. You lead the inspector to the director’s office, but you are not sure what the documents he needs are called. Which of the following document types contains this information?
MSDS
NDA
BYOD
MSDS
Material safety data sheets (MSDSs) are documents created by manufacturers of chemical, electrical, and mechanical products that specify the potential risks and dangers associated with them, particularly in regard to flammability and the possibility of toxic outgassing. A properly documented network should have MSDS documents on file for all of the chemical and hardware products used to build and maintain it. MSDSs can be obtained from manufacturers or the Environmental Protection Agency (EPA). Electrostatic discharges (ESDs), nondisclosure agreements (NDAs), and Bring Your Own Device (BYOD) policies are not concerned with the dangers inherent in building contents
Your new file server has two hard disk drives installed in it, and you want to create a fault-tolerant storage system using Redundant Array of Inexpensive Disks (RAID). Which of the following RAID levels can you use to achieve your goal?
RAID 10
RAID 5
RAID 1
RAID 1
RAID is a technology for storing data on multiple hard disk drives, providing fault tolerance, increased performance, or both. The various RAID levels provide different levels of functionality and have different hardware requirements. RAID 1 provides disk mirroring for fault tolerance and requires two or more disk drives. RAID 0 provides data striping only, with no fault tolerance. RAID 5 combines disk striping (blocks written to each disk in turn) with distributed storage of parity information for fault tolerance, but it requires a minimum of three disk drives. RAID 10 creates mirrored stripe sets and requires at least four disk drives. Therefore, RAID 1 is the only fault-tolerant solution you can use with only two disk drives
The iSCSI storage area networking protocol uses clients called initiators and servers called targets. However, on many SANs, there needs to be a way for the initiators to locate the targets. Which of the following technologies do iSCSI initiators use to locate iSCSI targets on the network?
ICMP
DNS
iSNS
iSNS
The Internet Storage Name Service (iSNS) is an application that provides iSCSI initiators with automated discovery of targets located on the network. iSNS can also function as a discovery service for Fibre Channel devices. Internet Control Message Protocol (ICMP) and Domain Name System (DNS) are not capable of registering iSCSI targets. iDNS does not exist
