Networks

This document provides answers to various questions related to computer networks, including definitions, common media and protocols, internet infrastructure, fiber-optic cables, ISPs, Ethernet switch and IP router, addresses and protocols, OSI layers, last mile connections, communication services, WiFi security, system logs, firewalls, packet sniffers, system monitors, WiFi analyzers, LAMP stack, domain registrars, virtual server setup, YUM, ping and tracert, managed switch, network topologies, Ethernet hub and switch, and handshaking and flow control.

Running head: NETWORKS
Networks
Name of the student:
Name of the university:
Author note:

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Networks
1. Define 'computer network' using the definition in class or a better one.
A computer network can be defined as a group of computer systems and some other
computing hardware devices that are linked together via communication channels using
data link communication process to facilitate the share of resources and communication
among a wide range of users. This digital form of telecommunication networks allows the
nodes to share the resources (Gaddala, Satish).
2. What are the most common media and protocols in today's computer networks?
There are generally three types of media in computer networks that includes coaxial
cable, twisted pair cable and fiber optic cable. The most current media type that is being
used is the radio wave media or wireless media which contains two layers namely the
physical layer and data link layer according to the OSI Model. This is used in LAN
technology known as Ethernet.
3. Who owns The Internet infrastructure aka The Internet Backbone? Describe it.
What are the most common media?
According to the Internet Corporation for Assigned Names and Numbers (ICANN), there
is no individual or business or any organization or management that owns the internet
infrastructure. It is a computer web that is distributed all over the world that has
interconnected networks (Wählisch, Matthias, et al.).
The most common media is the twisted pair cable, coaxial cable and fibre optic
chain used as the media for internet propagation.
4. How are fiber-optic cables better than copper for short and long-line
communications cables?
The fiber optical cables are faster than coaxial cables as the optical cables are thinner and
has greater bandwidth capacity as it carries data in the form of light, than the cooper
cables. The fiber optic cables are proved to be more eco friendly than the cooper and
coaxial cables. The fiber optical cable creates less attenuation, and is not easily breakable.

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5. Explain the 4 Tier system for classifying ISPs.
An Internet Service Provider is a group that delivers services for consuming and
accessing the internet. The ISP is divided in 4 tiers. The tier 1 has vast network and they
do not need to purchase a connection from the internet backbone. The Tier 2 are the
providers that have some interconnected agreements and has to purchase some the
connections. Tier 3 only purchases the connection for their internet which is distributed
broadly in the 4th Tier (Wichtlhuber, et al.).
6. What are the roles of the Ethernet Switch and IP Router in a SOHO or SMB
computer network? What protocols and addresses are used by each to carry their
traffic? What OSI layers do they work on?
The switch allows to connect many devices and maintain the traffic between two devices
from getting interrupted on the same network. Switches allow controlling various parts of
networks and monitoring the usage. It provides communication that is faster than internet
in SOHO and SMB computer network (Alani, Mohammed M).
Point to point protocol over Ethernet is used by each to carry their traffic.
The 4th layer of OSI model is the transport coat and works on the traffic protocols.
7. Name and describe each of these addresses and protocols: IP Address, MAC
Address, ARP, NAT, RIP, DHCP.
An IP Address is a numerical label assigned to each device connected to the computer
network using the internet protocol. An IP Address serves two main functions, it host
network interface identification and location addressing.
A media access control address or MAC address is a hardware identity number that
identifies each device on a network (Christopher, et al.).
The address resolution protocol (ARP) is a communication protocol that is used for
exploring the link layer address.
Network address translation is a process of remapping the IP address space of one
to another by modifying the information of network address.
RIT is the Routing Information Protocol that ensures that the information is shared in
routers during the traffic among interconnected LANS.
DHCP is the Dynamic Host Configuration Protocol is management protocol used on
UDP/IP

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8. On which OSI layer does each of these networking components operate? Ethernet
Switch, IP Router, Cable/RF.
At the 7th layer or the application coating of the OSI model the Ethernet switch is
operated.
IP Router is operated in the system layer that is sheet 3 and also on the second layer
that is the Data Layer (Frank, E. H., & Martin, R).
Cable or RF is operated in the last layer of the OSI Model which is the physical sheet.
9. What is 'The Last Mile' for network or telephone connections? What services are
offered over copper wire? What services are offered over fiber optic cables?
The last mile refers to the portion of the network telecommunications chain that reaches t
he end user's premises physically (Gómez-Cuba, et al).
Cable and DSL internet uses cables made from cooper for transmitting signals. Copper
broadband internet refers to T-carrier lines of T1, T3 and EoC.
Optical fiber wires are used in the broadcasting companies.
10. Characterize each of these common communications services and give it's
bandwidth and approximate cost: POTS, ISDN, T-1, T-3, OC-3, OC-12, FIOS, DSL,
Cable.
The plain old service from the standard telephone which had slow speed communication
and bandwidth is known as the POTS services.
ISDN, integrated services digital network is a set of communication standard for digital
transmissions. It has 128 kbit/s duplex bandwidth. It can cost $60.00 monthly and is
costly (Bocker, Peter.)
T1 carrier is a digital transmission line has 1.544 Mbps speed which is less costly than
ISDN.
T-3 line is a physical circuit that has high speed, media with 44.736 Mbps speed. It costs
$3,000 per month.
Oc-3 carries data on a third level of a synchronous optical network with 155.52 Mbps.
OC-12 is the optical carrier transmission that speeds up to 622.08 Mbit/s.
FIOS speeds up to 940 Mbps and costs $69.99 per month.
DSL’s speed ranges from 128 kbps to 3 Mbps. It costs $20 - $60 per month.
Cable has a bandwidth of 1000 Mbps and costs $80 per month.

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11. What's the problem with WiFi and security? What steps are needed to secure WiFi?
The security protocol that is used to protect the Wi-Fi connections is easy to break and
exposes wireless internet traffic. To secure the Wi-Fi connection the most important step
is to encrypt the Wi-Fi network (Shen, Wenlong, et al.). WPA is the strongest encryption
available for the Wi-Fi network.
12. What's found in the system logs /var/log/secure and /var/log/messages?
The system log file contains events logged by the components of the operating system. T
he operating system itself often predetermines these events. System log files may contain
device changes information, device drivers, system changes, events, operations, and more
.
13. In general, what does a firewall do? What features of Linux were demonstrated for
firewalling a server?
Software firewalls are installed in the devices like a software program which can be
customized and gives control over the function and protection area. It prevents
unauthorized access to the network and works as a barrier which controls incoming and
outgoing network traffic (Suh, Michelle, et al). Features like proxy servers, circuit
level gateway, packet filter, application gateway were verified in order to firewall a
server.
14. What does a 'packet sniffer' do? Name a common packet sniffer.
A packet sniffer is a tool that captures data packet all over the computer network. It is
similar as the process of wire tapping of a telephone network. A packet sniffer can be
either in the form of hardware or software which may allow the unauthorized access of
sensitive data (Verma, Atul, Ankita Singh)
The most common packet sniffer is tcpdump.

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15. What does a system monitor like Nagios do?
A system monitor like Nagios helps the organizations to identify and provide solution to
issues regarding IT infrastructure. The open source network monitoring solution can be
difficult to integrate into automatic processes of provisioning (Enterprises, Nagios).
16. Name two softwares for monitoring or probing network security.
Solarwinds Network Performance Monitor and Nagios XI are the two software for
monitoring or probing network security (Hernantes, et al)
17. What are 'WiFi Analyzers' and 'WiFi Spectrum Analyzers'? What does each show?
Why is a spectrum analyzer important for a network technician's toolkit?
Wi-Fi analyzers help to recognize Wi-Fi glitches and find the best network or the best
area for the router admittance point by revolving the device into an analyzer in wireless
network mode. Whereas the Wi-Fi spectrum analyzer measures the signal strength of the
Wi-Fi in a certain area or region.
Spectrum analyzer identifies the amount of the noise in the RF band. They assist
in configuration of a Wi-Fi network.
18. In the demo of setting up a LAMP stack: What does 'LAMP' stand for? What are
the roles of RackSpace and GoDaddy in the setup? What is 'reverse DNS' and why
is it important? How were dig and nslookup used to check the setup?
LAMP is the model for web service stacks. It is the abbreviation of its four unique open
basis components namely Linux Server, MySql, , Apache HTTP, RDBMS and the PHP
software design language.
Reverse DNS is a domain name mapping IP address which is opposite to the
forward DNS mapping domain. Reverse DNS is used for tracking website visitor.
Nslookup is used for troubleshooting DNS connected difficulties. It can be
castoff in collaborating and no cooperating mode where we have to type nslookup on the
command line of the nslookup command prompt.

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19. What does a domain registrar provide for a web server? What's the DNS manager
used for?
Domain registrar manages the reservation of internet domain names. DNS management
software controls the domain name system server clusters. This reduces the human error
during editing complex DNS data.
20. What were the few major steps in the class demo of setting up and securing a virtual
server? Include the two that required a credit card to complete...
The major steps of setting up a virtual server are user formation, network, package
management, , configuration, updating installation, , Firewalls and iptables, NTP
Configuration, Daemon Configuration, Securing SSH, Further Hardening and logging
and SE Linux. The daemon formation and securing SSH requires payment before
configuration.
21. As the server was set up, this command was run:
22. yum install gcc make automake autoconf libtool bind-utils openssl openssl-devel
mod_ssl sendmail sendmail-cf mailx dovecot
What it 'yum' and what does it do? What is the purpose of each component
installed?
YUM or Yellowdog Updater Modified is both an open basis knowledge line and a
graphical bundle tool for the Linux systems based on RPM (Red Hat Packet Manager). It also
enables users and system administrators that easily installs, updates and removes or search a
system for software packages.
23. What's 'ping' used for? What does 'tracert' show?
Ping is used to ensure that the user is actually using the computer as the host. Ping works
by sending ICMP request to specified location.
The tracert command shows several details of the path that isbtaken by a packet
from the computer to the specific destination.

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24. What functions does a 'managed switch' provide that a cheap switch doesn't.
Security risk, higher downtime due to no resiliency are the main reason to chose managed
switch over the cheap switch. The managed switch does not provide higher downtime and
hence prioritizes the traffic.
25. Which of the network security tools mentioned in class did you install? What do they
show?
I installed ARGUS as the network security tool. Argus is free and open source tool that is
available for analyzing traffic in network. It shows efficiency in depth analysis of network
data. Argus stands for Audit record Generation and Utilization. The comprehensive
reports are received through big chunks (Bhuyan, et al.)
26. Sketch and give a practical application for each of the network topologies sketched
and discussed in class: Serial, Bus, Star, Tree, Ring, and Mesh.

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(Pandya, Kartik )

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27. Explain these statements: An Ethernet Hub involves both Bus and Star networks. An
Ethernet Switch is inherently more secure than an Ethernet Hub.
To expand a LAN, we can connect the Ethernet switch and hub to a router with multiple
ports. The joining between the switches or hubs and the routers may require either
straight-thru or cusp (null-modem) chains, contingent on the router's competences (species
of obtainable ports) and the hubs and switches.

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28. How are these signals used? RTS, CTS, ACK, NACK.
RTS is the Request to Send and CTS is the clear to Send mechanism that is used in
wireless networking for feuding the frame collisions that are introduced by the hidden
nodes. Whereas ACK is the acknowledgement which is the confirmation of the receipt.
NAK is the Negative Acknowledgement sent to the station receiving corrupted packets.
29. What are handshaking and flow control in networking? What are hardware and
software flow control? Describe TCP's handshaking to establish a connection. Descibe
the IP's 'sliding window' flow control.
The steps of verifying the connection and the speed for the device waiting to be authorized
is known as handshaking.
Hardware flow control uses RTS/CTS or DTR/DSR. These are the dedicated signal
wires. Whole software flow control sends signal by normal data wires in which the signal
send DCQ1 or DC3 Control bytes.
TCP uses a three way handshake to connect. Before client tries to attach to a server, the s
erver must first connect to a port and listen to it to open it for connections.
The sliding window is process also known as windowing which is used by the
transmission control protocol. This controls the flow of packets between two computers
and network hosts.
30. Describe 'packetization'. What elements do ethernet frames and internet packets have
in common? What addresses are used in each. What is a CRC and how is used to help
ensure error-free data transmission.
The process of gathering data into packets according to a fixed protocol is known as
packetization.
Ethernet frames and internet packets have a header and trailer for the packets. This frames
the network data. MAC address is the physical address used in the network.
CRC are the cyclic redundancy codes that detects the errors
31. In general, what is a 'meshed network'? Name two examples of meshed networks.
What are 'fat tree' and 'spine and leaf' network architectures? Which network
controllers are important for ARM64 SoC chips to implement spine and leaf?

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A meshed network is defined as the topology of a local network consisting of
nodes like infrastructure devices, switches, bridges which directly connects with other
nodes dynamically cooperating with each other to efficiently route data from clients.
Two examples of meshed networks are-
1. ALOHA network or packet radio networks that were first used in Hawaii
2. Google Wi-Fi
Fat tree network architecture: This type of network topology is used in multicomputer
systems. The architecture consists of 2 to 360 computing nodes that are arranged in a
circuit of fat tree network. In this type of architecture, each node has its own local
memory that gets mapped by other nodes.
Spine- leaf network architecture: In this type of network architecture, a series of leaf
switches from the layer of access. The switches are fully meshed to form a series of spine
switches.
Open flow network supervisors are significant for ARM64 SoC chips in order to tool
spine and leaf planning.
32. Discuss these methods of managing traffic on networks. In which types of networks is
each commonly used? CSMA/CD, CSMA/CA, Token Passing, Polling, IP.
CSMA/CD: Standard ethernet networks makes use of the CSMA/CD in order to monitor
the traffic of the network. It is a type of contention protocol.
CSMA/CA: CSMA/CA is a network contention protocol that is used during transmission
using the 802.11 standard. It is generally used by Wireless LAN networks.
Token passing: In token passing method of network management, a special packet known
as token mingles around the circle cable from computer to computer. In this method, the
computers need to wait for a free token in order to transmit data across the network.
Usually local area networks use these types of network management method.
Polling: In the polling-based network management method, computers need to wait for an
external device in order to check the readiness of the system. It is generally used in wide
area systems.
IP: Internet Protocol management method helps in tracking the information that gets
transferred in the network. It is mainly used in the computer networks.
33. What three networks are essential for Business, eBusiness, and personal computing
these days?

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LAN and WAN are used in Business networks, internet or the world-wide
network is used in e-business and local area networks are used in personal computing.
34. Give a brief history of telecommunications infrastructure and regulations for
telegraph, telephones, long-line carriers, and the internet. Describe Ma Bell, Regional
Bells, Verizon, and CLECs. Include approximate years of maturity from each, and
important legislative and regulatory policies.
The era of telecommunication started in the year 1830. The communication first
started with the use of smoke signals. In the early 1980s first the telephone loop circuits
were used. This gave rise to the first commercial telegraph line. Gradually the era
continued and gradually gave rise to internet era.
Ma Bell- The bell receiver system was known as the Ma Bell. The organization contained
of 24 Bell operating businesses. The legislative policy that was included in Ma Bell was
the Communication Act.
Regional Bell- Regional bell is a telephone operating company in US.
Verizon- Verizon is one of the global leaders in communication and technology
providing 4g and 5g wireless network services.
CLECs- is a local competitive exchange carrier in US and Canada. It is one of the
telecommunication providers competing with other established carriers.
35. How are telegraph and telephone signals different? Why was telegraph important for
decades after telephone service was common?
A telegraph is ae meant for transferring and receiving messages over long
distances whereas telephone signals are sound that are converted from telephone into
electric signals with the help of cables and communication channels.
The impact of telegraph on the society was greater than any other impact as it changed
the way by which information was transferred from the working environment to the
industries.
36. Which companies merged to become AT&T, and when did the merge? What was the
Telecommunications Act of 1996? When was the 'Breakup of Ma Bell' and what
happened in the years following it? What is the ITU and what did it accomplish in the
mid-90s?
AT&T was acquired by Comcast in the year 2002. The AT&T merged with
Cingular wireless LLC in the year 2004.
The Telecommunication Act of 1996 is the first major telecommunication law. The law
aimed at letting anyone to enter into the field of communication and compete with other
business telecommunication organisations.

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The breakup of Ma Bell occurred in January 8, 1982. After the breakup of Ma Bell, the
companies that were formed from AT&T were acquired by Bell Atlantic in the year
1996.
ITU- ITU is International Telecommunication Union which is an agency under the
United States. Its purpose is to coordinate the telecommunication operations throughout
the world.
The modem technology was adopted into the ITU standards in the mid-90s.
37. How many bits are in IPV4 and IPV6 addresses? How many addresses does each
provide?
There are 32 bits present in the address of IPV4 and 128 bits that are present in
IPV6 network address.
The IPV4 addresses are considered in three kinds that are unicast, multicast and broadcast
reports.
The IPV6 addresses are considered into three categories namely unicast, multicast and
anycast addresses.
38. Characterize each/any of these protocols used for business on The Internet: TCP/IP,
HTTP, CSS, PKI/SSL/TLS, SSH, SMTP, EDI, X12, HIPA, EDIFact, ACH, VOIP,
SIP, SOA/SOAP, SCADA.
TCP/IP protocol- The characteristics of TCP/IP protocol includes reliability, flow
control, connection, multiplexing, full duplex.
HTTP protocol- The HTTP protocol allows the servers of the web to exchange
information over the web.
39. What are the roles of IP Routers and Ethernet Switches in a residential, SOHO, or
SMB network?
Ethernet Switches mainly operates on the OSI layer 1. The ethernet switch
protocol allows the switch to learn about the MAC address of each device network. It
makes use of the MAC address to direct the traffic of the network providing additional
security helping in improving the performance of the network.

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On the other hand, IP routers helps in handling the traffic of small business networks by
connecting to the LANS of the private internet.
40. Characterize each of these common networks: PSTN, The Internet, Ethernet.
PSTN- The features of PSTN or Public Switch Telephone Network are as follows:
1. It allows subscribers to get connected by entering telephone numbers
2. After the network gets hanged up, the connection gets closed and the resources are
then available for other users.
3. The connections are used to transfer speech related information.
Internet- The characteristics of Internet are as follows:
1. It is global in nature
2. It in interactive in nature
3. It has easy accessibility
Ethernet- The features of ethernet are as follows:
1. It is less expensive
2. It produces high speed local area network.
3. It offers network with a network base of 10 base T
41. Describe the difference between packet switched and circuit switched networks.
Telephone connections are circuit-switched -- how does that differ from packet-
switched connections on the internet?
Packet switch and Circuit switch are two different switching methods. The main
difference between the two is that the packet switching is connectionless whereas the
circuit switch is connection oriented.
A telephone connection is a kind of circuit switch having connection between the two end
points in a network while in packet switch connection on the internet there is no visible
connection that is they are wirelessly connected.
42. What are the OSI and TCP network models? How did they influence the adoption of
Internet and Ethernet standards. What’s been the result decades later?
The TCP/IP model is a standard procedure which allows joining of hosts over the
system. The OSI model is a referencing model that allows communication of
applications overs a network.

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The OSI physical layer influenced the adoption of ethernet by signaling different variants
that were used in the ethernet. The Internet protocol that is carried over ethernet
considered some key technologies that gave rise to the internet.
43. Name each of the organizations and say which aspect of network or internet
addressing each regulates: IEEE, IANA, RIR, ICANN.
IEEE- the IEEE regulates the future of spectrum or internet networks
IANA- the IANA regulates the global addressing of Internet Protocols.
RIR- the RIR regulates the allocation of IP address and handles it to the next level.
ICANN- the ICANN asses and allocates the top-level domains in the new genre offering
content regulation.
44. Name each of the acronyms, describe the use of each network address, and tell which
organization regulates each: AS, MAC, IP, Domain Name.
AS- The full form of AS is autonomous system. The autonomous system are controlled
under one or more network operators on behalf of single administrative domain.
MAC- The full form of MAC is media access control and it is ideal for organisations
where there is requirement for not more than 4096 unique 48 bits numbers.
IP- The full form of IP is internet protocol and it is regulated by the nonprofit oversees
corporation named ICANN.
Domain Name- The domain name is also regulated by the ICANN for naming and
numbering the systems of the internet.
45. Name the two components of MAC addresses and how they're regulated. How many
bits in each of these network addresses? MAC, IPV4, IPV6
The two components of MAC addresses are the organizational unique identifier or
the OUI and the vendor assigned address.
Number of bits present in
MAC- 48 bits are present in MAC.
IPV4- 32 bits are present in IPV4.

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IPV6- There are 128 bits present in IPV6.
46. Characterize networks classified by size and name common media for each: WAN,
MAN, SCADA, LAN, SAN, CAN, PAN, BAN.
WAN-size of WAN ranges over a huge area of 100000-kilometer radius and its
common media is PSTN or Satellite Link.
MAN- MAN covers an area between 5 to 50 km in diameter and it can access through
any medium.
SCADA- is a system architecture that is used to control network data and their
communications.
LAN- LAN spans over a relatively small area. The media of LAN includes copper
coaxial cables and optical fiber cables.
SAN- SAN is a high-speed storage of networks that connects with servers and storage
devices.
CAN- The minimum size of CAN is 20 bytes and maximum is 1500 bytes. The network
media of CAN includes copper coaxial cables, copper twisted pair cables and wired
optical fibers.
PAN- The size of PAN ranges to about 10 meters. A PAN interconnects device within a
personal area.
BAN- BAN operates in devices within close proximity and ranges to maximum of 100
devices per network.
47. Name 3 common network media for PANs? What are SCADA networks and PLCs
and what media are commonly used in them? What network media are common for
LANs? What are CANs and where are they deployed?
Three common network media of PAN includes Bluetooth, personal digital assistance,
and cell phones.
SCADA- is a type of system software. Supervisory control and dat acquisition allows
organisations to control the process of the industries locally by monitoring and gathering
information locally.
PLCs- PLC or programmable logic controller is a type of digital controller that is used for
automation of industrial process such as controlling machines in factory and many more.
The common network media for LAN includes residences and small businesses.
CANs- Campus area network is a computer network made up of local area network. They
are deployed within a limited geographical area.

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48. What is 'the ground' and how is it important for copper-wired LANs? What must be
avoided when networking in large buildings or multi-building sites?
In a copper wired LAN, a shielded twisted pair of copper telephone wiring is
often termed as the ground. It helps in connecting home and business computers with the
telephone company.
While networking in large buildings it is necessary to avoid wireless solutions.
49. What is the 'last mile' in network connections? Name traditional digital circuits
provided as last mile connections by telephone companies. Name three services that
compete with traditional digital circuits in many areas.
Last mile in network connection is a phrase that is widely used in
telecommunication to refer to the final leg of the network in telecommunication in order
to deliver the services to the end users.
Traditional digital circuits that are provided as last mile includes subscribers line, coaxial
cable service drops and many more.
Three services that compete with traditional digital circuits are ISDN, TDM and CCS7
services.
50. What are LECs, ILECs, and CLECs? What legislation was important for the
development of CLECs?
LECs- LECs is defined as the local exchange carrier which is a telecommunication term
for local telephone company.
ILECs- ILECs or incumbent local exchange is one of the telephone company in US that
provides services locally to the BELL operating companies.
CLECs- Competitive local exchange carrier is one of the providers of telecommunication
competing with other established carriers.
The Telecommunication Act of 1996 was important for the CLECs to be developed.
51. Describe these WAN standards: Frame Relay, MPLS, SONET.
Frame relay: is a type of packet switching service in telecommunication, designed for
cost effective transmission of data between LAN.
MPLS- Multiprotocol Label Switching is a routing technique of protocol that is designed
to enhance the speed and shape of traffic across WAN.

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SONET- Synchronous Optical Networking is a standard for multiplexing protocols
allowing transfer of multiple bits of digital stream over optical fiber using LEDs.
52. What is T-Carrier and E-Carrier systems in the PSTN? Who uses each? Which has
somewhat higher bandwidth available?
T-carrier in PSTN is a series of system carriers that are industrialized by AT&T for digital
broadcast of multiplexed phone call.
E-carrier is one of the members of the sequence of transporter systems established by
AT&T. It is meant for transferring digital data by the method of time division
multiplexing.
Among T-carrier and E-carrier, T-carrier has higher bandwidth than e carrier.
53. Who is the ITU and who are their members? What did they accomplish by the mid-
90s?
The International Telecommunication Union is the agency of United States that
was founded in the year 1865.
The members of ITU includes different states and their zones around the globe.
In the mid of 90s US was dominated by many ITU venues which led to its
accomplishments.
54. Characterize each of these traditional telecommunications services. Give the
bandwidth provided by and a reasonable monthly cost for each: ISDN BRI, ISDN
PRI, T-1, T-3, OC-3, OC-12. Which are available on copper last-mile connections?
ISDN BRI- the bandwidth of ISDN BRI is 128kbit/s and its cost is about $60.00
ISDN PRI- the bandwidth of ISDN PRI is 64 Kbps and its cost is $400 to $500 per month
T-1- the bandwidth of T1 is 1.544Mbps and its cost is between $1000 and $15000 per
month
T-3- the bandwidth of T3 is 44.736 Mbps and its cost is $796 per month
OC-3- the bandwidth of OC3 is 156 Mbps and its price starts from $10000.
OC-12- the bandwidth of OC12 is 622Mbps and its cost is $4,000
55. Characterize each of these telecommunications services that compete with traditional
telephone company services. State the range of bandwidth and a reasonable monthly
cost for each: DSL, Cable, FTTD, WiMAX, Satellite.
DSL- The bandwidth of DSL ranges from 128 kbps to 3mbps. And its cost ranges to
$150.

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Cable- The bandwidth of cable is 1000Mbps and its cost is $50 to $100.
FTTD- The available bandwidth of FTTD is beyond 10G and its installation cost is
around $5.87 per foot.
WiMAX- The bandwidth of WIMAX ranges from 40 to 70 Mbps and its total installation
cost may exceed up to $200000.
Satellite- The bandwidth of Satellite is 40 MHz and its launching cost is between $10
million to $400 million.
56. What is PKI, TLS, and SSL certificates? What do they do? What Internet services do
they secure?
PKI certificate- this includes public key that are used for encrypting data. They help in
securing individual certificates for authenticating transactions that are done digitally.
TLS- TLS certificate verifies the digital certificate and sends random string bytes to
enable clients and servers to compute the underground key that is used for encoding the
data (Liu et al.).
SSL- SSL certificates are small files of data that encrypts the details of an organization
by activating the padlock and the https protocol allowing secured connection of web
servers (Möller et al.).
57. Name and describe three websites dedicated to network security.
Three websites that are dedicated to network security are-
1. Brian Krebs- the website is dedicated towards ensuring any attack or threat within the
network.
2. Errata Security- this website blog consists of two security researchers having huge
experience.
3. Sophos- it is dedicated towards publishing new threats that may affect any
organisation.
58. Name two of the best-known CAs. In general, what does a more expensive SSL
certificate mean? What is the risk of using an self-issued SSL certificate, or one issued
by an un-trusted CA?
Two best known CA are GeoTrust and GoDaddy.
A more expensive SSL certificate ensures the customers that they are interacting with a
trusted website and their information are free from any kind of threats (Kaul et al.).

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Self-issued SSL consists of data related to customer login and other credentials and they
are often prompted in web servers to display alerts because the certificate is not verified
by any trusted CA or certificate authority

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