Quiz Let Flashcards
osi model Application
Provides access to the network for applications and certain end-user functions. Displays incoming information and prepares outgoing information for network access.
osi model presentation layer
Converts data from the application layer into a format that can be sent over the network. Converts data from the session layer into a format that the application layer can understand. Encrypts and decrypts data. Provides compression and decompression functionality.
osi model session layer
Synchronizes the data exchange between applications on separate devices. Handles error detection and notification to the peer layer on the other device.
osi model transport layer
Establishes, maintains, and breaks connections between two devices. Determines the ordering and priorities of data. Performs error checking and verification and handles retransmissions if necessary.
osi model network layer
Provides mechanisms for the routing of data between devices across single or
multiple network segments. Handles the discovery of destination systems and
addressing.
osi model data link layer
Has two distinct sublayers: LLC and MAC. Performs error detection and handling for the transmitted signals. Defines the method by which the medium is accessed. Defines hardware addressing through the MAC sublayer.
osi model physical layer
Defines the network’s physical structure. Defines voltage/signal rates and the physical connection methods. Defines the physical topology.
TCP/IP Model Compared to OSI Model
Application layer: Application, Presentation and Session layer of the osi model
Transport layer:Transport layer
Internet layer: Network layer
Network interface layer: Data link layer
Physical layer
Loopback address
IPv4 127.0.0.1
IPv6 0:0:0:0:0:0:0:1 (::1)
Networkwide addresses
IPv4 public address
Global unicast IPv6 address ranges
Private network addresses
IPv4
- 0.0.0
- 16.0.0
- 168.0.0
IPv6
Site-local address ranges (FEC0::)
Autoconfigured addresses
IPv4
Automatic private IP addressing (169.254.0.0)
IPv6
Link-local addresses of FE80:: prefix
FTP
20 data transfres and 21 for listen to commands
SSH
22 TCP
Telnet
23 TCP
SMTP
25 TCP
DNS
53 TCP
POP3
110 TCP
NNTP
119 TCP
NTP
123 TCP
IMAP4
143 TCP
HTTPS
443 TCP
DNS
udp port 53
TFTP
UDP port 69
BOOTPS/DHCP
UDP port 67 for sending data to the server, and UDP port 68 for data to the client.
SNMP 161
UDP Port 161
MAC address
A MAC address is a 6-byte hexadecimal
address that enables a device to be uniquely identified on the network. A MAC address combines numbers and the letters A to F. An example of a MAC address is 00:D0:59:09:07:51.
CLASS A Address
A Class A TCP/IP address uses only
the first octet to represent the network
portion,
Class A addresses span from 1 to 126, with
a default subnet mask of 255.0.0.0.
and a Class C address uses three octets.
CLASS B Address
A Class B address uses two octets.
Class B addresses span from 128 to 191,
with a default subnet mask of 255.255.0.0.
CLASS C Address
Class C address uses three octets.
Class C addresses span from 192 to 223, with a default subnet mask of 255.255.255.0.
local loop back
local loop backThe 127 network ID is reserved for the IPv4
local loopback.
Steps 1 in Troubleshooting Methodology
Identify the problem: . Gather information. . Identify symptoms. . Question users. . Determine if anything has changed.
Steps 2 in Troubleshooting Methodology
Establish a theory of probable cause:. Question the obvious.
Steps 3 in Troubleshooting Methodology
Test the theory to determine cause:
After theory is confirmed, determine next steps to resolve problem.
If theory is not confirmed, re-establish new theory or escalate.
Steps 4 in Troubleshooting Methodology
- Establish a plan of action to resolve the problem and identify potential effects.
Steps 5 in Troubleshooting Methodology
Implement the solution or escalate as necessary.
Steps 6 in Troubleshooting Methodology
Verify full system functionality and if applicable
implement preventative measures.
Steps 7 in Troubleshooting Methodology
Document findings, actions, and outcomes
Virtualization
Virtualization makes it possible to take a
single physical device and make it appear
as if it is a number of stand-alone entities.
virtual switch
A virtual switch works the same as a physical
switch but enables multiple switches to exist on the same host, saving the implementation of additional hardware.
Network as a Service (NaaS)
Network as a Service (NaaS) is a cloud
computing model offered by many telecom
providers provided on demand in a pay as-
you-go model. OpenStack is the open source NaaS project.
NAT
NAT translates private network addresses
into public network addresses.
Link State routing protocols
A router that uses a link-state protocol
differs from a router that uses a distance vector
protocol because it builds a map of the entire network and then holds that map in memory. Link-state protocols include Open Shortest Path First (OSPF) and Intermediate System-to-Intermediate System (IS-IS).
What do Hop mean in routers
Hops are the means by which distance vector
routing protocols determine the shortest way to reach a given destination. Each router constitutes one hop, so if a router is four hops away from another router, there are three routers, or hops, between itself and the destination.
RIP
Routing Information Protocol (RIP) is a distance-vector routing protocol used for TCP/IP.
Example of distance vector routing protocols
Distance-vector protocols in use today include Routing Information Protocol (RIP and RIPv2), Enhanced Interior Gateway Routing Protocol (EIGRP), and Border Gateway Protocol (BGP).
Switch improvement over a HUB
Switches introduce micro segmentation,
by which each connected system effectively
operates on its own dedicated network connection.
PoE
Power over Ethernet (PoE) is a technology
that enables electrical power to be transmitted over twisted-pair Ethernet cable. The power is transferred, along with data, to provide power to remote devices. These devices may include
remote switches, wireless access points,
VoIP equipment, and more.
Default gateways
Default gateways are the means by which a device can access hosts on other networks for which it does not have a specifically configured route.
Internet Protocol
IP is a network protocol responsible for providing addressing and routing information
TCP/IP
The TCP/IP suite is used by all major operating systems and is a routable protocol.
DHCP/BOOTP
DHCP/BOOTP is a network service that automatically assigns IP addressing information.
In a network that does not use DHCP, you need to watch for duplicate IP addresses that prevent a user from logging on to the network.
Subnetting
Subnetting is a process in which parts of the host ID portion of an IP address are used to create more network IDs.
APIPA
APIPA is a system used on Windows to automatically self-assign an IP address in the 169.254.x.x range in the absence of a DHCP server.
DNS
DNS resolves hostnames to IP addresses.
PAT
Port Address Translation (PAT) is a variation on NAT in which all systems on the LAN are translated into the same IP address but with different port number assignment.
Quality of Service
Quality of Service (QoS) enables administrators to predict bandwidth use, monitor that use, and control it to ensure that bandwidth is available to applications that need it.
Half-duplex
Half-duplex mode enables each device to both transmit and receive, but only one of these processes can occur at a time.
Full-duplex
Full-duplex mode enables devices to
receive and transmit simultaneously.
UTP
UTP cabling is classified by category.
Categories 5/5e and 6/6a offer transmission
distances of 100 meters.
F-type connectors
F-type connectors are used with coaxial
cable, most commonly to connect cable
modems and TVs. F-type connectors are
a screw-type connector.
fiber connectors
SC, ST, LC, and MT-RJ connectors are
associated with fiber cabling. ST connectors
offer a twist-type attachment, and SC, LC, and MT-RJ connectors are push-on.
RJ-45/11
RJ-45 connectors are used with UTP cable and are associated with networking applications. RJ-11 connectors are used with telephone cables.
Plenum-rated cables
Plenum-rated cables are used to run cabling through walls or ceilings.
horizontal cabling
The horizontal cabling extends from the telecommunications outlet, or network outlet with RJ-45 connectors, at the client end. It includes all cable from that outlet to the telecommunication room to the horizontal cross-connect.
Vertical cable
Vertical cable, or backbone cable, refers to the media used to connect telecommunication
rooms, server rooms, and remote locations and offices.
MDF/IDF
Main Distribution Frame (MDF) and Intermediate Distribution Frame (IDF) define types of wiring closets. The main wiring closet for a network typically holds the majority of the network gear,
including routers, switches, wiring, servers, and more.
demarcation point
A network’s demarcation point refers to the connection point between the ISP’s part of the network and the customer’s portion of the network.
802.11a
5GHz
Up to 54Mbps
25 to 75 feet
CSMA/CA
802.11b
2.4GHz
Up to 11Mbps
Up to 150 feet
CSMA/CA
802.11g
5Ghz/2.4GHz
Up to 600Mbps
175+ feet
CSMA/CA
Bus network topology
The bus network topology is also known as a linear bus because the computers in such a network are linked using a single cable called a trunk or backbone.
If a terminator on a bus network is loose, data communications might be disrupted. Any other break in the cable cause the entire network segment to fail.
Star configuration
In a star configuration, all devices on the network connect to a central device, and this central device creates a single point of failure on the network.
wired mesh topology
The wired mesh topology requires each computer on the network to be individually connected to every other device. This configuration provides maximum reliability and redundancy for the network.
wireless infrastructure/ ad hoc
A wireless infrastructure network uses a centralized device known as a wireless access point (AP). Ad hoc wireless topologies are a peer-to-peer configuration and do not use a wireless access point.
802.2
802.2, the LLC sublayer, defines specifications for the Logical Link Control (LLC) sublayer in the 802 standard series.
802.3
802.3 defines the carrier sense multiple access with collision detection (CSMA/CD) media access method used in Ethernet networks. This is the most popular networking standard used today.
EMI
Many factors cause EMI, including computer monitors and fluorescent lighting fixtures.
Copper-based media are prone to EMI, whereas fiber-optic cable is immune to it.
Crosstalk
Data signals might also be subjected to crosstalk, which occurs when signals from two cables, or from wires within a single cable, interfere with each other.
Attenuation
The weakening of data signals as they
traverse the media is called attenuation.
straight-through cable
A straight-through cable is used to connect systems to the switch or hub using the MDI-X ports.
Cross over cable
In a standard crossover cable, wires 1 and 3 and wires 2 and 6 are crossed.
T1 crossover cable
A T1 crossover cable is used to connect two T1 CSU/DSU devices in a back-to-back configuration.
media converter
When you have two dissimilar types of network media, a media converter is used to allow them to connect.
Shaping by application
Shaping by application: Administrators can control traffic based on the types of network traffic and assigning that category a bandwidth limit.
Documentation
Documentation should also include diagrams of the physical and logical network design. The physical topology refers to how a network is physically constructed—how it looks.
The logical topology refers to how a network
looks to the devices that use it—how it functions.
RAID 0
RAID 0 offers no fault tolerance and improves I/O performance. It requires a minimum of two disks.
RAID 1
RAID 1, disk mirroring, provides fault tolerance
and requires two hard disks. Separate disk controllers can be used—a strategy known as disk duplexing.
RAID 5
RAID 5, disk striping with distributed parity,
requires a minimum of three disks—the total size of a single disk being used for the parity calculation.
full backup
In a full backup, all data is backed up. Full
backups do not use the archive bit, but they
do clear it.
Incremental backups
Incremental backups back up all data that
has changed since the last full or incremental
backup. They use and clear the archive bit.
Differential backups
Differential backups back up all data since
the last full or differential backup. They use
the archive bit but do not clear it.
GFS (grandfather, father, son)
GFS (grandfather, father, son) is a commonly
implemented backup strategy
wire crimper
A wire crimper is a tool that you use to attach media connectors to the ends of cables.
Wire strippers
Wire strippers come in a variety of shapes
and sizes. Some are specifically designed to strip the outer sheathing from coaxial cable, and others are designed to work with UTP cable.
Punchdown tools
Punchdown tools are used to attach twisted-pair network cable to connectors within a patch panel. Specifically, they connect twisted-pair wires to the IDC.
Voltage event recorders
Voltage event recorders are used to monitor
the quality of power used on the network or by network hardware.
Temperature monitors
Temperature monitors keep track of the
temperature in wiring closets and server
rooms.
Toner probes
Toner probes are used to locate cables hidden in floors, ceilings, or walls and to track cables from the patch panel to their destination.
Protocol analyzers
Protocol analyzers can be hardware- or software-based. Their primary function is to analyze network protocols such as TCP, UDP, HTTP, FTP, and more.
TDR
A TDR is a device used to send a signal through a particular medium to check the cable’s continuity
OTDR
An OTDR performs the same basic function
as a wire media tester but on optical media.
Packet sniffers
Packet sniffers are either a hardware device
or software that eavesdrop on transmissions
that are traveling throughout the network.
Throughput testers
Throughput testers identify the rate of data
delivery over a communication channel.
Port scanners
Port scanners are a software-based utility.
They are a security tool designed to search
a network host for open ports on a TCP/IP-based network.
netstat -a
The netstat -a command can be used on a Windows-based system to see the status of ports.
ping 127.0.0.1
You can ping the local loopback adapter by
using the command ping 127.0.0.1. If this command is successful, you know that the TCP/IP suite is installed correctly on your system and is functioning.
tracert
tracert reports how long it takes to reach each router in the path. It’s a useful tool for isolating bottlenecks in a network. The traceroute command performs the same task on UNIX and Linux systems.
ARP
ARP is the part of the TCP/IP suite whose
function is to resolve IP addresses to MAC
addresses.
netstat
netstat is used to view both inbound and outbound TCP/IP network connections.
nbtstat
nbtstat is used to display protocol and statistical information for NetBIOS over TCP/IP connections.
ipconfig
ipconfig shows the IP configuration information
for all NICs installed in a system.
ipconfig /all is used to display detailed TCP/IP configuration information
ipconfig /renew is used on Windows operating systems to renew the system’s DNS information.
When looking for client connectivity problems using ipconfig, you should ensure that the gateway is set correctly.
ifconfig
The ifconfig command is the Linux equivalent of the ipconfig command.
nslookup /dig
The nslookup command is a TCP/IP diagnostic tool used to troubleshoot DNS problems. dig can be used for the same purpose on UNIX and Linux systems.
firewall
A firewall is considered a logical security measure and is one of the cornerstone concepts of network security.
At its most basic, a firewall is a device that has more than one network interface and manages the flow of network traffic between those interfaces.
DMZ
A DMZ is part of a network on which you place servers that must be accessible by sources both outside and inside your network.
IDS
An IDS can detect malware or other dangerous
traffic that may pass undetected by the firewall. Most IDSs can detect potentially dangerous content by its signature.
IPS
An IPS is a network device that continually
scans the network, looking for inappropriate
activity. It can shut down any potential threats.
access control list
An access control list (ACL) typically refers to specific access permissions assigned to an object or device on the network. For example, wireless routers can be configured to restrict who can and cannot access the router based on the MAC address.
When a port is blocked
When a port is blocked, you disable the capability for traffic to pass through that port, thereby filtering that traffic.
VPN
A VPN extends a LAN by establishing a remote connection, a connection tunnel, using a public network such as the Internet.
PPTP
PPTP creates a secure tunnel between two points on a network, over which other connectivity protocols, such as PPP, can be used. This tunneling functionality is the basis for VPNs.
VPNs created and managed
VPNs are created and managed by using
protocols such as PPTP and L2TP, which
build on the functionality of PPP. This makes it possible to create dedicated point-to-point tunnels through a public network such as the Internet.
L2TP authenticates
L2TP authenticates the client in a two-phase process. It authenticates the computer and then the user.
IPSec uses two separate protocols
To create secure data transmissions, IPSec
uses two separate protocols: Authentication
Header (AH) and Encapsulating Security Payload (ESP).
PPPoE
PPPoE (Point-to-Point Protocol over Ethernet) is a protocol used to connect multiple network users on an Ethernet local area network to a remote site through a common device.
RDP
The RDP and ICA protocols allow client systems to access and run applications on a remote system, using that system’s resources. Only the user interface, keystrokes, and mouse movement are transferred between the client and server computers.
AAA
AAA defines a spectrum of security measures, policies, and procedures that re combined to create a secure network.
Authentication
Authentication refers to the mechanisms used to verify the identity of the computer or user attempting to access a particular resource. This includes passwords and biometrics.
Authorization
Authorization is the method used to determine
if an authenticated user has access to a particular resource. This is commonly determined through group association—a
particular group may have a specific level of
security clearance.
Accounting
Accounting refers to the tracking mechanisms
used to keep a record of events on a system.
Terminal Access Controller Access Control System+ (TACACS+)
Terminal Access Controller Access Control
System+ (TACACS+) is a security protocol
designed to provide centralized validation
of users who are attempting to gain access
to a router or Network Access Server (NAS).
Kerberos
Kerberos is one part of a strategic security solution that provides secure authentication services to users, applications, and network devices. It eliminates the insecurities caused by passwords being
stored or transmitted across the network.
public key infrastructure (PKI)
A public key infrastructure (PKI) is a collection of software, standards, and policies that are combined to allow users from the Internet or other unsecured public networks to securely exchange data.
A public key
A public key is a nonsecret key that forms
half of a cryptographic key pair that is used
with a public key algorithm. The public key
is freely given to all potential receivers
A private key
A private key is the secret half of a cryptographic key pair that is used with a public
key algorithm. The private part of the public
key cryptography system is never transmitted
over a network
A certificate
A certificate is a digitally signed statement that associates the credentials of a public key to the identity of the person, device, or service that holds the corresponding private key.
