1480 networking
Cite two types of main network topologies
Physical topology / Logical topology
what is a physical topology?
- indicates arrangement of different elements of network
- reflect physical layout of devices and cables to a form a connected network
What is a logical topology?
- refers to the abstract representaion of how data flows and is transmitted within a network (independent of its physical layout)
- how softeare controls access to network resources
- how specific resources are sared to the network
what is NOS?
Network Operating System(also called a server operating system)
a software that connects multiple devices and computers on the network and allows them to share resources on the network
what are 4 advantages of NOS?
- highly stable due to central server
- provide good security
- upgration of new technology and hardware can be easily implementd
-provide remote access to servers from different location
cite 5 features of the NOS
- printers and application sharing on the network
- file system and database sharing
- provide good sercurity by using functionality like user authentication and access control
- create backuos of data
- inter-networking
cite 5 functions of the NOS
-creating and managing user accounts on the network
- contorolling access to resources on the network
- provide communication services between the device on the network
- monitor and troubleshoot the network
- configuring and managing the resources on the network
cite two types of network models
peer-to-peer network model / client-serve netowrk model
what are 2 advantages of a peer-to-peer network model?
- simple to configure
- less expensive to set up and mantain than other types of network
what are 3 disadvantages of peer-to-peer networl model?
- not scalable
- unsecure
- no centrally backup for files and folders
what is a peer-to-peer network model's characteristics?
the OS(operating system) of each computer on the network is responsible for controling access its resources without centralized control, which means no computer has more authority than another; each computer controls its own resources and communicates directly with other computers
describe a client-server network model?
resources are managed by the NOS via a centralized directory database.
what is AD?
Active Directory
The centralized directory database that contains user account information and security for the entire group of computers on a network.
what is AD DS?
Active Directory Domain Service
The Active Directory service that manages the process allowing a user to sign on to a network from any computer on the network and get access to the resources that Active Directory manages.
cite 4 advantages of a client-server network model
- user accounts and passwords to the network are assigned in one place
- access to multiple shared resources can be centrally granted to a single user or groups of users
- problem on the network can be monitored, diagnosed, and often fixed from one location
- it's easier to add users and devices to a client-server network
what is network services?
A resource the network makes available to its users, including applications and the data provided by these applications.
what is client-server applications?
Data or a service requested by one computer from another.
what kinds of protocol are used in web service?
HTTP, SSL, TLS and HTTPS
HTTP (Hypertext Transfer Protocol) is layered on top of an encryption protocol, such as SSL(Secure Sockets Layer) or TLS(Transport Layer Security), the result is HTTPS(HTTP Secure)
what kinds of protocol are used in email services?
SMTP, POP3, IMAP4
the client uses SMTP(Simple Mail Transfer Protocol) to send an email message to the first server, then the recipients mail server delivers the message to the receiving client using POP3(Post Office Protocol, ver3) or IMAP4(Internet Message Access Protocol)
what is NIC?
Network Interface Card
The component in a computer or other networking device that enables the device to connect to the network and communicate with other devices. Also called network adapters.
cite 5 kinds of physical topology
a star topology, a bus topology, a hybrid topology, hub-and-spoke topology and a ring topology
what is a router?
A network layer device that uses logical addressing information to direct data between two or more networks and can help find the best path for traffic to get from one network to another.
what is MAN?
MAN (metropolitan area network)
A network of connected LANs within a limited geographical area, such as multiple city government buildings around a city’s center.
what is WAN?
WAN (wide area network)
A network that spans a long distance and connects two or more LANs.
cite OSI model from layer7 to layer 1
7. Applicatoin layer
6. Presentation layer
5. SEssion layer
4. Transport layer
3. Network layer
2. Data link layer
1. Physical layer
what is EF?
entrance facility
the location where an incoming network service to make the transmission from WAN or MAN which are managed by ISP to LAN or CAN which are managed by the customer.
what is demarc?
the device that marks where an ISP’s network ends and the organization’s network begins
what is MDF?
Main Distribution Frame
the centralized point of interconnection between an organization’s LAN or WAN and a service provider’s network.
Also known as the ER(equipment room)
what is a data room?
an enclosed space that holds network equipment. These spaces might have requirements for size, clearance around equipment, wall materials, and physical security (such as a locked door)
what is a patch panel(patch bay)?
A wall- or rack-mounted panel where cables converge in one location.
what does VoIP(Voice over IP) do?
the use of any network (either public or private) to carry voice signals using TCP/IP protocols.
what does a voice gateway device?
- converts signals from a campus's analog phone equipment into IP data that can travel over the Internet
- converts VoIP data from an internal IP network to travel over a phone company's analog telephone lines.
what kind of protocol used in an application layer by voice gateways to initiate and. maintain connections is?
SIP(Session Initial Protocol)
what is an end user device or application that gives the user access to VoIP services on a network?
VoIP phone
what is IDF?
Intermediate Distribution Frame
a junction that provides an intermediate connection between the MDF and end-user equipment on each floor and in each building.(there can be many IDFs connecting internal portions of the network)
The ANSI/TIA standards specify at least one IDF per floor, although large organizations may have several data rooms or closets per floor to better manage the data feed from the main data facilities.
cite standards of rack setting for height, width and depth.
Height - Rack height is measured in rack units (RU or U) with the industry standard being 42U tall—about 6 feet. Half-racks are usually 18U–22U tall.
Width - Equipment racks come in a standard 19-inch frame, meaning that the front is 19 inches wide. You might also come across 23-inch racks.
Depth - Rack depths vary considerably between manufacturers.
why does it need to consider minimizing cable clutter?
to prevent airflow blockages and heat buildup.
In a typical rack system, airflow through the chassis is designed to move from front to back. In data centers containing multiple rows of racks, a hot aisle/cold aisle layout pulls cool air from vents in the floor or from nearby, low-lying wall vents into the rows of racks. The hot air aisles are used to direct the heated air away from the racks into exhaust vents for cooling.
how long is the maximum allowabe distance for horizontal cabling?
100m
90m to connect the network device in the data room to a data jack on the wall in the work area.
10m(maximum) to connect the wal jack to a workstation.
what does it cause when terminating twisted-pair cabling leaves more than 1 inch of exposed cable before a twisted-pair termination?
crosstalk
that is possibility of transmission interference between wires, a phenomenon
describe a prescribed bend radius
the radius of the maximum arc into which you can loop a cable without impairing data transmission.
why does a network professinal need to verify each segment of cabling you install transmits datat reliably by using a cable tester?
to prevent you from later having to track down errors in mutiple, long stretches of cable
(Continuity)
why should cables be loosely cinched?
this will leads to difficult-to-diagnose data error.
what does it help by covering and conduits cable?
to prevent damaging from rolling chairs or foot traffic
to reduce the risk of damnage from pests or water
what is EMI?
Electromagnetic Interference
A type of interference that can be caused by motors, power lines, televisions, copiers, fluorescent lights, or other sources of electrical activity.
why should a cable be installed at least 3 feet away from fluorescent lights or other sources of EMI?
to reduce the possibility of noise(interference) that can affect your network's signals
what is the usage of Nmap?
Network Mapper is a scannning tool
to assess large networks quickly and provide comprehensive, customized information about a network and its hosts.
what are three examples of tools to creat a network diagrams?
Nmap / Zenmap / Cisco
cite the six processes of the system life cycle to manage inventory
• reuirements analysis
Identify network requirements and business needs.
• design planning
Progress from big picture goals to detailed decisions.
• development and testing
Purchase equipment and test before deploying.
• implementation
Deploy new equipment to replace old equipment, and continue testing to achieve a new, stable baseline.
• documentation and maintenance
Apply effective monitoring techniques to detect and address problems, and keep documentation updated.
•. evaluation
As improvements are needed or devices break down, perform a cost–benefit analysis to identify devices reaching the end of their life cycle and determine whether to discard, replace, or upgrade.
cite six kinds of business documentation to track network assets and resources
RFP(request for proposal)
MOU(memorandum of understanding)
MSA(master service agreement)
SOW(statement of work)
SLA(service-level agreement)
MLA(master license agreement)
what is RFP(request for proposal)?
A document requesting that vendors submit a proposal for a product or service that a company wants to purchase.
what is MOU(memorandum of understanding)?
A document presenting the intentions of two or more parties to enter into a binding agreement, or contract. usually not a legally binding document.
what is MSA(master sevice agreement)?
A contract that defines terms of future contracts.
what is SLA(service-level agreement)?
defines the level of service expected by a customer from a supplier
what is MLA(maste license agreement)?
a legal contract between the City of Vacaville and a wireless carrier (also known as a wireless provider), which identifies the City as the licensor and the wireless carrier as the licensee.
which layer is MAC address used?
layer 2, Data link layer
which layer is IP address used?
layer 3, Network layer
how does IP address work with routers at layer 3(network layer)?
Routers, which function primarily at layer 3, check IP addresses to determine which network a message is destined for.
what is a port? and what does a port do at transpport layer(layer 4)?
a number used by the transport layer to find an application.
It identifies one application among several that might be running on a host.
what is FQDN?
Fully Qualified Domain Name
A host name plus domain name that uniquely identifies a computer or location on a network.
what is the domain name?
The last two parts of an FQDN, such as mycompany.com. Usually, a domain name is associated with the company’s name and its type of organization, such as a school or nonprofit organization.
what is the host name?
identifies the individual computer on the network.
Ftp - given to an FTP server
www - often the host name assigned to a computer running a web server.
what is ICANN? and what they do?
Internet Corporation for Assigned Names and Number
a nonprofit organization charged with setting many policies that guid how the internet works
maintain and assign IP address
what does identify the first 24 bits of MAC address?
OUI(Organaizationally Unique Identifier)
identifies the NIC's manufacturer
what does the last 24 bits make up?
the extension identifier or device ID and identify the device itself.
Manufactures assign each NIC a unique extension identifier, based on the NIC's model and manufacture date.
what is the purpose does switches use MAC address?
to identify devices on the local are network(LAN)
As each device communicates on the network, the switch identifies the sending device’s MAC address from its transmitted message.
The MAC address is stored in a MAC address table that maps each MAC address to a physical port on the switch.
what Windows command outputs a computer's MAC address?
ipconfig /all
what is the static IP address?
An IP address that is manually assigned to a device and remains constant until it is manually changed.
what is the dynamic IP address?
An IP address that is assigned to a device upon request and may change when the DHCP lease expires or is terminated.
what does a DHCP server manage?
the dynamic distribution of IP addresses to devices on a network.
what does a subnet mask help?
helps determine which part of an IP address identifies the network and which part identifies the host within that network.
what can I know by using the information of a subnet mask and IP address?
a computer can determine if another computer with a given IP address is on its own or a different network.
what kind of devices can be a gateway?
a computer, router, firewall, or other device that a host uses to access another network.
what does the default gateway do?
The gateway device that nodes on the network turn to for access to the outside world.
- provides a connection to all resources outside the local network when static routes aren’t available (which is most of the time).
how to identify network information or host in the IPv4 address?
class A - 1.x.y.z ~ 126.x.y.z, the first 8 bits for network information.
class B - 128.0.y.z ~ 191.255.y.z, the first 16 bits for the network information.
class C - 192.0.0.z ~ 223.255.255.z, the first 24 bits for the network information.
the rest of bits other than the network information are used to identify hosts.
class D - 224.x.y.z ~ 239.x.y.z, used for multicast transmissions
class E - 240.x.y.z ~ 254.x.y.z, not available for general use
what is called Class A,B and C licensed IP address that are available for use on the internet?
public IP address
definite the public IP address
an IP adderess that is valid for use on public networks, such as the Internet.
what is the private IP address
IP addresses that can be used on a private network but not on the Internet.
IEEE recommends the following IP address ranges for private use:
class A - 10.0.0.0 through 10.255.255.255;
class B - 172.16.0.0 through 172.31.255.255;
class C - 192.168.0.0 through 192.168.255.255.
compare a static IP address and a dynamic IP address
static IP address - manually assigned by the network administrato
dynamic IP address - automatically assigned by a DHCP server each time a computer connects to the network.
what is the main function of NAT?
Network Address Translation
When private devices need access to other networks or the Internet, a public-facing gateway (such as a router or firewall) substitutes the private IP addresses used by computers on the private network with its own public IP address.
what is the advantage of using NAT?
Network address translation
good for security; the gateway hides the private network’s hosts behind this one address.
what are the main function of PAT?
Port Address Translation
- assigns a separate TCP port to each session between a local host and an Internet host
ex) When the Internet host responds to the local host, the gateway uses PAT to determine which local host is the intended recipient.
help facilitate communication between devices by ensuring that data reaches the correct application or service on the destination device.
in which situation is SNAT that is a kind of NAT used?
Small home networks with only a single public IP address provided by its ISP use SNAT thatthe gateway assigns the same public IP address to a host each time it makes a request to access the Internet.
Private network (private IP address) -> router using NAT -> uses SNAT -> public IP address -> internet
how does DNAT(Destination Network Address Translation) be used in transport layer?
the destination IP address is changed to the private IP address of the host inside the network when a message sent to the public IP address reaches the router managing DNAT.
Internet (public IP address) -> router using NAT -> uses DNAT -> private IP address
DNAT for incoming messages
how can you rewrite this IPv6 address in shorhand?
2001:0000:0B80:0000:0000:00D3:9C5A:00CC
2001::B80:0000:0000:D3:9C5A:00CC
or
2001:0000:B80::0000:D3:9C5A:00CC(recommended)
- only one block of 0000 can be ::
- leading zeroes in a four-character hex block can be eliminated
in what situation is said dual stacked?
When a network is configured to use both IPv4 and IPv6 protocols.
what does the last 64 bits (4 blocks) of an IPv6 address identify?
the interface and are called the interface ID or interface identifier.
cite the unicast address(a type of IPv6 address)
Global address / link local address / loopback address
what are the global address's characteristics?
- can be routed on the internet(similar to public IPv4 address)
-most begin with the prefix 2000::/3
"/3" indicates that the first three bits are fixed and are always 001.
what are characteristics of the link local address?
- can be used for communicationg with nodes in the same link
- begin with FE80::/10
- sometimes written as FE80::/64 that are not allowed past the local link or on the internet
the first 10 bits(indicated by /10) of the reseved prefix are fixed and remaining 54 bits in the 64-bit prefix are all zeroes
what are characteristics of the loopback address?
- can be used to test that an interface and supporting protocol stack are functioning properly
- ::1/128(consists of 127 zeros followed by a 1)
what is the address prefix of unique local unicast?
FC00::/7 (fist 7 bits are always 1111 110)
FD00::/8 (first 8 bits are always 1111 1101)
what is the address prefix of the multicast?
FF00::/8 (first 8 bits are always 1111 1111)
What command shows you a computer’s TCP/IP configuration?
ipconfig
what is the role of sockets?
consists of both a host’s IP address and a process’s TCP or UDP port, with a colon separating the two values.
ex) the standard port for the Telnet service is TCP 23. If a host has an IP address of 10.43.3.87, the socket for Telnet running on that host is 10.43.3.87:23.
cite 4 types of port
Well-known ports - range from 0~1023, used for Telnet, FTP and HTTP
Registered ports - range from 1024~49151, used temporarily by processes for nonstandard assignments to increase security
Dynamic and Private ports - range from 49152~65535, open for use without restriction
what is the purpose of "nslookup" command line?
finds the internet protocol (IP) address or domain name system (DNS) record for a specific hostname
what does the event viewer provide to troubleshoot?
the diagnosis of a printer problem and recommended steps to fix the problem
what is ping that is command line? what does it help?
A TCP/IP troubleshooting utility that can verify TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network. Ping uses ICMP (Internet Control Message Protocol) to send echo request and echo reply messages.
which protocol is used to get the echo request and echo reply with the ping utility?
ICMP(INternet Control Message Protocol)
a lightweight protocol used to carry error messages and informaton about a network.
when you want to know if you have internet access, how can you do to verify?
use the ping in command prompt.
"ping google.com"
Ping a host using its host name to verify you have Internet access and name resolution, and Google.com is a reliable site to use for testing.
what can you know by using ping -a +IP address?
Test for name resolution and display the host name to verify DNS is working.
ex) ping -a 8.8.8.8 will display Google's public DNS server
what kind of information can I get by using dig utility?
Use dig to query DNS nameservers for information about host addresses and other DNS records.
A utility available on Linux and macOS that provides more detailed domain information than nslookup.
what is the IP scanner used for?
A tool used to gather information about all devices connected to a network, including host names, manufacturer names, operating systems, IP addresses, MAC addresses, interfaces used, and open ports with running services.
IP scanner > Nmap, Zenmap and ipconfig
what are common IP setting issues you might encounter?
- Incorrect IP address
- Duplicate IP address
- Incorrect subnet mask
-Incorrect gateway
- Incorrect DNS or DNS issues
what problem can the "ping+host name(ex.google.com) check?
Name resolution issues
Pinging a host using its host name can verify you have Internet access and functioning name resolution (DNS) services because the host name must first be resolved before the host can be located and pinged.
in which layer are TCP and UDP used?
layer 4, transport layer
in which layer is IP address used?
layer 3, network layer
the header identifies the IP address of the destination host and the message is called a packet.
cite three characteristics of TCP in its role as a reliable delivery protocol
- connection-oriented (ensure the connection is established)
- sequencing and checksums (ensure the response)
- flow control (control speed, volume)
what is the purpose of the TCP three-way handshake?
The TCP three-way handshake establishes a session before TCP transmits the actual data, such as an HTTP request for a web page.(transport layer right befor session layer, layer 5)
what are characteristics of UDP(User Datagram Protocol)?
- connectionless protocol
-no connection is established by UDP before data is trasmitted
- provides no hadshake to establish a connection, acknowledgement of transmissions received, erro checking, sequencing, or flow control
- more efficient and faster than TCP
in which layer does ICMP(Internet Control Message Protocol) operate?
Layer 3, network layer
what is the role of ARP(Address Resolution Protocol)? and in which layer does ARP operate?
works in conjunction with IPv4 to discover the MAC address of a node on the local network and to maintain a database that maps local IPv4 addresses to MAC addresses.
Layer 2, Data link layer
what is the arp-a command line used for?
displays and modifies the Internet-to-adapter address translation tables(lists devices with MAC address on the network) used by the Address in Networks and communication management.
cite two sublayers within the data link layer,layer 2
- LLC(logical link control) sublayer
identifies the type of message and handle multiplexing, flow and error control, and reliability
- MAC sublayer
identifies the destination and source MAC addresses, provides the checksum in the frame's trailer
which protocol's header incudes the source MAC address?
Ethernet
a header for TCP and UD at the transpor layer includes a port to identify the communicating aplication on the source host.
IP identifies the IP addres of the source host.
an ARP table maps MAC address to what information?
IPv4 address
ARP works in conjuction with IPv4 to discover the MAC address of a node on the local network and to maintain a database that maps local IPv4 addresses to MAC address.
what is the protocol that used at layer 3, network layer to defines encryption, authentication, and key management for TCP/IP transmissions?
IPsec (Internet Protocol Security)
what are two protocols that methods of encrypting TCP/IP transmissions en route between the client and server using public key encryption technology?
SSL/TLS
SSL- Secure Sockets Layer
TLS- Transport layer Security
in which layer does SSL operate?
application layer, layer 7
in which layer does TLS?
transport layer, layer 4