345 Midterm

1000 MB

1 GB

1000 Bytes

1 KB

1000 KB

1 MB

8 binary bits(smallest data communication) = 1 symbol or 1 letter

1 byte(smallest data storage)

Windows Ping (4 replies) = CentOS ?

# ping (must stop manually)

False

At layer 2 of the OSI model, the network to network data communiations or the routing is handled.

True

In the UNC protocol used for network resource access, a server's IP address can be used in place of its name.

Star

In the above picture, the network topology is (like a snowflake)

Mesh

In the above picture, the physical network topology is (star in pentagon)

False

In this UNC example \\mis1\myresources, "mis1" is the name of the network share that is located on the the server named "myresources".

False

It is considered that Ethernet was invented in 1980.

Network

Layer 3 of OSI

False

Layer 4 of the OSI model is called the network layer.

Presentation

Layer 6 of OSI

Application

Layer 7 of OSI

Physical

Layer one of OSI

00-0C-29

Refer to the following physical address: 00-0C-29-E5-84-25 What is the vendor ID or the vendor's OUI?

255.248.0.0

Suppose a IPv4 network has 19 bits in its host ID portion. What will be the subnet mask for this network?

Transport layer protocols:

TCP and UDP

True

The Internet layer in the TCP/IP model is equivalent to the Network layer in the OSI model.

False

The OSI model has 5 communication layers

Full-duplex

The above picture describes which type of transmission mode in terms of data flow directions? (information going in both directions between two computers)

True

The acronym WAN stands for Wide Area Network.

False

The data carried by TCP protocol can not be tracked.

False

The default networking model for Windows operating system is the domain based model.

False

The physical address is defined at layer 3 of the OSI model.

/

The root directory of the entire file system hierarchy of a Linux OS is represented by:

True

To manage a large number of client computers effectively, they can be put in a Windows domain which is created on servers called domain controllers.

True

To protect an enterprise network, we can consider using firewalls, perimeter networks or security zones.

Data sending

Top to Bottom

False

UDP protocol provides guaranteed delivery of data.

True

Using Windows advanced firewall, any TCP or UDP port can be blocked.

OSI layer 3

What layer device is a router

layer 2

What layer hardware is a switch?

broadcast

When a server on a network sends a message to all computers or devices on the network, which type of data casting is this?

Class A

Which class is the following classful IP address? 12.17.5.3

netstat

Which of the following CLI commands can be used to view the active communication connections or sessions on a computer?

80

Which of the following WKP port number is typically used on Web servers? 25 53 80 636

Microsoft Azure

Which one of the follwoings is Microsoft's major cloud computing technology?

Microsoft Office 365

Whihc of the followings is an example of Software as a service (SaaS)?

PaaS flexibility

YES (some flexibility available)

IaaS flexibility

YES (ultimate flexibility)

4

You are working on a computer and see that it has an IPv6 address of 2001:0001::41f0:f763. How many groups of 0s have been compressed

o simplex

a sends to b only, b cannot go back to a (traditional radio, traditional cable)

o full duplex

a sends to b, b sends to a, can at the same time (telephone, modern computer systems)

Group policy definition

a set of rules that provides the centralized management and control of user accounts and computer accounts in an AD environment

routing protocols

adapt quickly to changes in the network

Operating System

manages all the resources (resource allocator) and controls all of the operations (program executions) on a computer

• UDP (user datagram protocol) (network data) (gps)

o Connectioin-less (path is determined during transmission) o Non-reliable o Uses best-effort o "network state data' transmission

• TCP pg.46 (user data) (no gps) (receiver tells sender they got the message)

o Connection-oriented (path is determined first before transmission) o Uses three-way handshake (client, server,...) o Reliable o For user data transmission

• Dropping leading zeros

o Fe80::184:e9f8:a71b:304

• Approaches for error detection

o Redundancy: Using some redundancy can allow us to detect, and possibly correct, some errors of this type The disadvantage is: too much overhead o Parity bit

Concept of peer to peer (bitcoin)

• All computers on a network are equal to each other • Limitation: small number of users (around ten)

Classful IPv4 > CIDR (Classless Inter-Domain Routing)

• CIDR is a subnetting method that enables administrators to place the division between the network bits and the host bits anywhere in the address, not just between octets o Prefix: number of binary bits in the network portion in IP address

WAN (Wide Area Network)

• Connect remote sites • Covers hundreds or thousands of miles

data-casting

(how many computers can receive the message at the same time)

True

Microsoft Windows desktop client operating systems are generally designed for two scenarios: home users and business users.

RIP

Which of the followings is a type of routing protocol that determines the optimal routing path based on the number of hops in a route between a source and destination computer?

Windows ipconfig = CentOS ?

# ifconfig

Windows Ipconfig /? = CentOS ?

# man ifconfig

M=the total number of subnets (outcomes) required

# of bits needed? N=log(m)/log(2)

extended star

(based of star, 4 small stars with central connection point, used on campus) <EXTENDED OR HYBRID (can divide them up into basic) TOPOLOGY

hierarchical

(central connection point of top, used on campuses(this)) <EXTENDED OR HYBRID (can divide them up into basic) TOPOLOGY

ring

(closed loop, computers connected to one another, travel in one direction,90s) <BASIC TOPOLOGY

star

(late 80s to 90s, low cost, open standard, easy to operate, need central connection point, most widely used)<BASIC TOPOLOGY

True

A cloud service typically has a monthly allowance on the amount of traffic included in the monthly cost.

2001::9e76:04c9:009b:3f57:0e98

A computer has an IPv6 address of 2001:0000:0000:9e76:04c9:009b:3f57:0e98. How can this address be simplified using the zero compression approach?

2001::9e76:4c9:9b:3f57:e98

A computer has an IPv6 address of 2001:0000:0000:9e76:04c9:009b:3f57:0e98. How can this address be written using both the dropping leading zeros and zero compression methods?

LAN

A group of computers are connected in a single location such as in a room or on a floor of a building. What is this type of network called?

False

A router is a type of networking device that is typically used to connect client devices or desktop computers to a network.

True

A subnet is a network that can be independently managed.

False

An NAT device can only convert private IP addresses to public IP addresses.

00-C0-F0-27-64-E2

An example of a physical address is ____. 02-AA-BB-CC-E2 00-C0-F0-27-64-E2 137.28.100.100 AA-02-AA-BB-CC-E2-AF

False

Deploying a firewall to protect an entire enterprise network is called domain-level security.

Microsoft Azure

Microsoft Azure is a growing collection of integrated cloud services—analytics, computing, database, mobile, networking, storage, and web services.

True

Microsoft Windows firewall is a software program that can be configured to block incoming or outgoing data traffic based on TCP port numbers.

Airport

Microsoft Windows firewall supports 3 types of location profiles or settings. Which one of the followings is NOT one of them?

10 seconds

To transmit 1,000,000,000 bits of data using a device that has a data transmission rate of 100Mbps, how long will it take?

SMTP

When you send an email, which of the following application layer protocols will be used? SNMP POP HTTP SMTP

ping

Which of the following CLI commands can be used to check end to end connectivity?

SaaS

Which of the following cloud services can NOT be configured?

256.10.1.100

Which of the following is NOT a valid IP address? 137.28.10.10 256.10.1.100 137.28.100.100 20.30.40.50

TCP

Which of the following protocols is not a routing protocol?

IP

Which of the following protocols is not an Application Layer protocol? SMTP POP3 IP FTP

Microsoft Office 365

Which of the followings is NOT a cloud computing service model?

Enable automatice update on a client computer.

Which of the followings is a way to enhance client security?

Windows Server 2016

Which of the followings is not a client OS?

ifconfig

Which one of the following commands allows us to view IP address assigned to a CentOS computer?

switch

connects computers

• Netstat -n

converts foreign to whole numbers instead of letters

o half duplex

data travels one direction at a time, a sends to b, b sends to a, can't at the same time (walkie talking system)

OS mobility

desktop OS vs mobile OS

Computer network

group of connected computers and devices that can transmit data and communicate to each other using the same protocols(set of rules that govern a connection process, how computers connect with one another, must follow same protocol)

Why GP?

group policy centralized management of user and computer configuration settings throughout a network

range coverage

-each wireless network is identified by service set identifier (ssid) -antenna and range

Client OS characteristics

-for individual users -2-4 CPUs -optimized for foreground applications -running foreground applications is the default for client OS

switch

-has physical ports for multiple connections -transmits data based on physical addresses -defined at layer 2

using NAT to protecting an internal network

-intranet: internal LAN -private IP addresses --10, 172, 192 -NAT --translates private IPs to public --translate public IPs to private

OSPF (Open Shortest Path First)

-link state routing protocol defined in RFC 2328 -uses link costs with the lowest values to determine the best path to the destination -widely used on large enterprise networks

5 tasks that can be centrally managed

-manage and control user desktop settings -implement security -run scripts -enable folder redirection -automate software deployment

TCP 20 Bytes

User Transport Layer

use of a proxy server

understanding proxy servers -caching -filtering -content checking

o Client port numbers

dynamic range 49152-65535 not registered anyone can use 16384 whole/port numbers, can have that many sessions, local is client

domain

logical group of computers and users -characterized by centralized authentication and administration -authentication provided through centralized Active Directory -UWEC network domain and group policy

10 gigabit ethernet

10000 mbps

Server

provide service

Presentation Layer

• Determines how to format and present the data o Coding o Compression o Encryption(SSI

mesh

(star where they are all connected to each other(full mesh)[number of links: {n*n-1}/2], very expensive because it requires many cables to be connected, most dependable among all of them, building to building, site to site connections)<EXTENDED OR HYBRID (can divide them up into basic)) TOPOLOGY

False

A computer's MAC or physical address is defined at layer 3 of the OSI model.

False

A router is an OSI layer 4 device.

24

Based on the IPv4 addressing system, how many binary bits are allocated to the host ID portion of a class A network?

126

Based on the classful IPv4 addressing system, how many valid class A networks are available?

8

Based on the original IPv4 addressing system design, how many binary bits are allocated to the host ID portion of a class C IP address?

a server

Based on the screen shot above from a computer, we can say this computer is a [adjust for best performance of : background services]

8

Given the following IP address with its subnet mask. How many bits are in the host ID portion: 190.120.150.166, subnet mask 255.255.255.0

True

Given the following IP address with its subnet mask. The network ID is: 158.20.0.0 158.20.50.66, subnet mask 255.255.0.0

True

IEEE 802.3 represents a family of Ethernet networking standards.

True

IEEE802.3an standard specifies a data transmission rate of 1 Gbps.

True

IaaS allows ultimate flexibility in cloud service configurations.

yum install httpd

Which of the following allows a web site to be created on a CentOS server?

IaaS

Linode offers cloud service at which service level?

SaaS flexibility

NO (SLA is typically used to manage cloud performance)

UDP 8 Bytes

Network Transport Layer

True

The location of a cloud server is a factor to consider when we choose a cloud server to use.

OS editions

home editions vs enterprise/professional editions

OS user orientation

home/casual users vs enterprise users

Server OS other name

multi-user OS

• Redundancy approach: repeat each bit

o Repeat each bit twice. For bit x, transmit xx. If the receiver gets two different bits, it requests retransmission. This is an error-detecting code - it allows one error to be detected, but it is not error-correcting, since retransmission is necessary o Repeat each bit three times. For each bit x, transmit xxx. Now the receiver can correct a single error

• The minimum number of binary bits (x) are needed to represent m different outcomes

o X=[logm/log2] > open square brackets round up o Number of bits for 35 students log(35)/log(2)=5.12928=6 bits Always used 5 digits after decimal place Log(2)=.30103

o Broadcast

one-to-all (sent to everyone on the network; emergency messages, notifications) - what makes a computer network alive, simple, user-friendly [application dependent?]

o Multicast

one-to-many (selective casting, subscription casting; subscriptions to something)

exploring types of names used in networks

progression of name resolution -FQDN (computer name + domain name) -domain name -computer name (NetBIOS name; often called host name) -port number L4 -IP address L3 -MAC address L2

OS openness

proprietary OS vs open source OS

Windows Domain = CentOS ?

realm

cloud install PHP language

yum install PHP

Original Ethernet

• 10 Mbps • Use csma/cd protocol • Use bus topology

cloud OS update

yum update

Windows Firewall Settings

-software (or hardware) that protects your computer in two ways: --monitors incoming traffic from the internet or a network --monitors outgoing traffic from your computer to the internet or a network --rule types -location context --public --home/work --domain

MAC address table/bridge table

-switch -map a physical port to a MAC address

remote connection

-telnet protocol used -PuTTY is a popular program --free and open source terminal emulator for remote connections -it supports several network protocols including SCP, SSH, telnet, rlogin, and raw socket connection -it can also connect to a serial port

file transfer

-transfer files to the server in the cloud using SFTP protocol (FTP over SSH) -use: filezilla --filezilla is a free software, cross-platform FTP application, consisting of filezilla client and filezilla server. client binaries are available for Windows

name of a client computer

-way to identify a computer on a network -also called 'host name' -using default name is not a good practice -rename a client computer is often needed --must have local administrative rights

FastEthernet

• 100 Mbps standards • Use csma • Star topology

Client OS other names

individual OS, desktop or mobile OS

domain-based

most modern networks are based on ? client-server computing

local (standalone) computer vs. domain computer

name of client computer: -BIOS name ('host name') -host name vs. FQDN -FQDN: host name + domain name -FQDN is associated with domain

• Common ports:

o 21 FTP o 22 Secure shell o 23 telnet o 25 SMTP o 110 POP3 o 143 IMAP4 o 80 HTTP o 443 HTTPS o 53 DNS

Parity check code

o A bit string has odd parity value of 0 if the number of 1s in the string is odd o A bit string has odd parity value of 1 if the number of 1s in the string is even

• Zero compression

o Can only do this once o Fe80:0000:0000:0000:0184:e9f8:a71b:0304 Fe80::0184.....

• A, B, C, D, E pg. 92 • Classful IPv4 has 5 classes

o Classes D and E reserved o Class A 1-126 o Class B 128-191 o Class C 192-223

o Unicast

one-to-one (email, purchasing off amazon)

o Special apps

registered port number range 1024-49151 some registered 48128 whole/port numbers, can have that many sessions

routing

the process of deciding the optimal path to send a packet -based on a certain math algorithm

routers

use dynamic routing protocols to build their route tables and advertise route information

o Server port numbers

well known port numbers (wkp) 0-1023 reserved with iana 1024 whole/port numbers, can have that many session, foreign is server

cloud install Apache server

yum install httpd

Ethernet

• Ether + network > EtherNet > Ethernet • Invented initially as a LAN technology by Robert Mecalfe and David Boggs at Xerox in 1973 • Defined at layer 2 with layer 1 specifications • Standardized as IEEE 802.3 standards

OS computer roles

client OS vs server OS

bus

(single networking cable to have all computers connected, used early 70s-80s, cable break causes network to be paralyzed, singles travel in both directions) <BASIC TOPOLOGY

data rate

(specifies how fast device can transmit to a network, or how much data in one second is transmitted)

802.11ac trends

-developed from 2011 to 2013 and approved in January 2014 -will be rolled out in waves

RIP (Routing Information Protocol)

-distance vector routing protocol -uses the number of hops to determine the best path to a destination -used on small networks

Wireless Ethernet (WLAN)

-802.11 family of networking standards -emerging WIFI technology

What is Cent-OS?

-CentOS Linux is a community-supported distribution derived from Red Hat Enterprise Linux (RHEL) -CentOS Linux is functionally compatible with RHEL -CentOS Linux is no-cost and free to redistribute -Each CentOS version is maintained for up to 10 years --each CentOS version is periodically updated (roughly every 6 months) -a new CentOS version is released approx. every 2 years -has client version vs server version

router example

-Cisco 2600 series router -modular -expandable -un-fixed interface

DNS hierarchy

-DNS root servers -top level domain DNS servers -second level domain DNS servers -third and lower level domain DNS servers

router

-OSI layer 3 device -basic internet building block -transmits data based on IP address -examines each IP packet, what is network ID? -maintains routing table for network to network data transmissions -routing table stores info about network connections -uses routing protocols to determine the best path -interconnect independent subnets

File sharing and security

-UNC format --\\servername\share-name --\\IP address\share-name --\\servername.domain-name\share-name -proper credentials needed to access the share --domain user account for domain resource sharing --local used account needed for local sharing -permissions (R, change/write, full control)

2 types of cloud service environment

-VM based cloud service -Containerized cloud service

domain model with Active Directory

-a domain can support hundreds and thousands of domain clients -AD DS -DC -Group Policy

Group Policy

-a way to set up specific configurations for users and computers within an Active Directory domain -can use group policy to control desktop settings -can use group policy to control user behaviors

perimeter network

-area between the internet and intranet -single firewall vs dual firewall

characteristics of a strong password

-at least six characters long -contains characters from each of the following groups: uppercase and lowercase, numbers, symbols -has at least one symbol character in the 2nd through 6th positions (~ ! @ # $)

client computer security: areas to consider

-checking your windows update settings -virus protection -user account control: creating strong passwords -firewall settings -domain security: join/register a client to a domain -network share and security: UNC, permissions

Microsoft Internet Information Services (IIS)

-configure a firewall to control incoming traffic -using IIS as an example -web service as server role

client/server domain-based networking

-dedicated server: physical computers dedicated to run one or more services to serve the needs of the users of other computers on a network -centralized domain-based management -super masters (domain controllers (DC)) -dedicated network staff (expertise) -highly scalable (thousands of users) -one DC up to 5000 users

when will routing be needed?

-determining network IDs -if not on same subnet, routing will be needed and default gateway used

Server OS characteristics

-manages access to a centralized resource or service on a network -designed for multi-user environment -optimized to run back-end applications (web services, ad services, file services) -multiprocessing capabilities (multiple CPUs) --MS server up to 128 CPUs -multiple server roles exist

what would be a server computer (hardware)?

-multiple CPUs -redundant power -redundant network connection -have to run 24/7

Peer to peer or workgroup

-network of computers that allow each other to their files, printers, or internet connection -by default, all Windows computers are placed in a workgroup named WORKGROUP -not scalable (network size: 10-20) -no central security (issue=inherent security weakness)

characteristics of a complex password

-not contain user's account name or parts of full name with 2 consecutive characters -at least six characters long -contains characters from 3/4 groups: uppercase, lowercase, numbers, symbols

essential characteristics of cloud computing

-on demand self service -broad network access -resource pooling -rapid elasticity -measured service

Operating System Basic Functions

-provide an interface to access the hardware (booting a computer) -create an operating environment (API) to run applications -support networking and communications by implementing network protocols and managing network resources (file and print sharing)

WIFI: Wireless ethernet implementation details

-same frame formats as wired Ethernet -CSMA/CA utilized -star topology -family of standards -data rate evolves rapidly

Domain Controllers (DCs)

-servers that host domain security database -requires at least one server system configured as a domain controller -a dedicated server -where domain policy is edited and stored

Network security risks on the internet

-the internet is considered an un-managed network --all internet addresses are public --the internet is TCP/IP based-known to anyone --the world wide web travels over the internet -organizational networks (internal) need to be protected from the internet --use a firewall (hardware; network device) --create an intranet and protect it using NAT --use proxy server --create a perimeter network using firewalls

18.7 Million bits

A book has 550 pages. Assume each page has 50 lines, and each line has 85 characters. If we convert this book into a digital document with no overhead, what is the amout of data generated?

True

After a Windows domain has been created, if a user wants to log on to the domain, then a domain user account must be centrally created.

True

After a client computer has joined to a domain, it can be centrally controlled by domain controllers.

True

An IP address in CIDR notation is 66.16.76.25/16. The equivalent subnet mask is 255.255.0.0

False

An example of UNC format for network file sharing is c:\MyData\spring2018.

Data Receiving

Bottom to top

True

CentOS is an open source OS developed based on Red Hat Enterprise Linux (RHEL).

Types of Physical Ports

E-Ethernet (10 Mbps) F-FastEthernet (100 Mbps) G-GigabitEthernet (1 Gbps) 10G-GigabitEthernet (10 Gbps)

True

Each IPv6 address consists of two components: the network ID and the host ID. Host ID is also called extended unique identifier (EUI).

True

Each IPv6 address has 32 hexadecimal digits.

True

Each type of data commuication application needs to be supported by a corresponing application layer protocol.

22 Bytes

Ethernet Header

4 Bytes

Ethernet Trailer

65536

How many TCP or UDP port numbers are possible?

True

If data needs to be transmitted from one subnet to another, a router and a default gateway will need to be used.

16384

In the IPv4 addressing system, how many class B network ID's are possible? (You may use the MS-Windows or your Calculator.)

49514

In the screen shot above, for the highlighted line, what is the TCP port number used on the local computer? Proto: TCP; Local Address: 10.34.0.80:49514; Foreign Address: 192.231.219.68:80; State: Time Wait

80

In the screen shot above, for the highlighted line, what is the TCP port number used on the remote computer? Proto: TCP; Local Address: 10.34.0.80:49514; Foreign Address: 192.231.219.68:80; State: Time Wait

Transport

Layer 4 of OSI

Session

Layer 5 of OSI

Data Link

Layer two of OSI

cloud computing definition

National Institute of Standards and Technology (NIST) defines cloud computing as: a model for enabling convenient and on-demand network access to a shared pool of configurable computing resources, and these resources (such as networks, servers, storage, applications, and services) can be rapidly provisioned and released with minimal management effort or service provider interaction

False

On a client/server network, all computers are equal to each other.

False

On a computer, only 10 communication sessions can be established as needed.

True

On a domain-based Widnows network, a client computer is identified by its FQDN.

True

On a domain-based Windows network,a domain user account can be used to log on to the domain using any domain computers.

False

On an enterprise network where a DMZ is created, typically key data servers such as personnel database servers are put in the DMZ.

routing protocols examples

RIP-Routing Information Protocol OSPF-Open Shortest Path First

Client

Receive service

True

The logical address is used to determine on which network or subnet a computer is located.

True

The data string 110010011 with 1 odd parity bit is received. Based on the algorithm learned in class, we can say no transmission error has occurred.

True

The password "iS345$589" is a strong password.

Internet Information Services

Which of the following allows a web site to be created on a Windows computer?

cloud start the web server

systemctl start httpd systemctl enable httpd(start at boot)

Active Directory Domain Services (AD DS)

technology that runs the domain security database

gpresult.exe/R

view group policy on a client

Gigabit Ethernet

• 1000 mbps standards

IPv4 protocol

• Defined at the internet layer • Responsible for: o Logical addressing system o Routing Source computer sends packets via local LAN Router forwards packet to another router until destination

Network Layer

• Determines the best route to destinations • Using logical addresses o IPv4 - allows google internet to scale up with no technical difficulties • Protocols: o IPv4 o IPv6 o ARP o IGMP o ICMP: Internet Control Message Protocol > PING command uses this from your computer to destination computer; PING to Death attach overwhelm network o IPSec o RIP - best route determination o OSPF - best route determination • Ipconfig > CLI • CLI: Command Line Interface vs. GUI: Graphic User Interface

Network interface card (network adapter)

• Each computer/device needs a NIC or adapter to be connected to a network • Each NIC provides a device with at least one unique physical address o Each physical address uniquely identifies a device locally o Exception: NIC used on servers typically has multiple physical addresses

Transport Layer

• End to end connectivity o Host to host o Device to device o User to user • Handles flow control, reliability, and error checking o TCP (for user data) Connection-oriented Three-way handshake o UDP (for network configuration data) Connectionless Best effort o User generation and machine generated data both go to layers

Session Layer

• Establish, maintain, and terminate sessions • Could be combined with other layers such as transport layer • Computer networks use port numbers to define sessions • Channel between point a and point be .______. Phone call can have people on call waiting, have multiple browsers open-multiple sessions open, 2^16 bits=65536 sessions, VISA can process like 35000 a second-each connection is a session o Number my computer > number remote computer

TCP/IP Model is a variation of the OSI model

• Four Layers o Application layer o Transport layer o Internet layer o Link layer

LAN (Local Area Network)

• Group of connected devices • Covers a small area; a floor, several floors in a building, a building, or a campus • Use of ethernet standard is dominant

Common application layer protocols

• HTTP o Allow web browsing • HTTPS o Allow secure web browsing • FTP • Telnet (mainframe age) • Remote Desktop Services o Microsoft RDP o For Mac, VNC (Virtual Network Computing)

Understanding the dual IP stack - coexisting

• IPv4-mapped IPv6 addresses o ::FFFF:192.168.1.5 OR o ::FFFF:C0A8:0105 (converted decimal to hex) o First 80 bits set to zero - 16 bits all binary ones - 32 bits IPv4 address

Application Layer

• Interfacing with user applications • Many application layer protocols available: DNS, HTTP, FTP, TFTP, DHCP, LDAP, POP3, SMTP, IMAP, SNMP, SMB • Web browsers: Internet Explorer, Firefox, ... HTTP • Email: Outlook, Mail, ... SMTP/POP3/IMAP • https://facebook.com > user data starts at top goes to bottom • File Transfer: WinSCP • Remote connection: puTTY

Application Layer Protocols: example

• Main protocols o SMTP o POP3 Other protocols: used to transmit network data • TFTP: often used for file transfer on network devices • SNMP • ICMP o Ping Command

Data Link Layer

• Mainly about linking a computer to a LAN • Uniquely identify a computer/device o Physical addresses • Logical Link Control o (LLC): link network segments together o Standardized by IEEE 802.2 committee • Media Access Control (MAC) o Defines physical addresses = MAC add. = hardw... add. o Standardized by different IEEE 802.x committees Ethernet Token Ring • Physical address: HEX, unique similar to IP address

Networking Enterprises (campus network: made up of two stars, also rings or meshes; ECASD; WiscNet)

• Multiple sites are connected • Dedicated server • Centralized policy and security management • Enterprise has no formal definition o Typically thousands of users o May have dozens of administrators

IPv6 2^128 bits

• Next generation internet addressing system o Resolves many problems in IPv4 o 128 bits long Can address 340 undecillion IP addresses 1 undecillion = 36 zeros > 10^36 340 x 10^36 o Accommodates foreseeable global network growth • Uses four digit groups of hexadecimal numbers, separated with using colons o Hexadecimal notation • Composed of 64 bit network ID, 64 host addressing bits; host called extended unique identifier • 2^64 = network addresses globally • 8 groups of four hex digits; 1 hex = 4 bits

Physical Layer

• Responsible for transmitting, receiving bits • Using transmission medium (cables, radio/wireless signals) • Different connectors used > physical interfacing (UTP connectors, etc.)

Subnet Mask

• Subnet mask is not network or IP address - only a way to separate the network address from the host address • Integral part of IPv4 networking • Each IP address has a subnet mask • Subnet mask o 32 bit long o 1's designate network bits, 0's designate host bits o Network ID + Host ID = Ind. IP address

Subnetting and IPv4 network

• The process of dividing an IPv4 network into subnets • Steps: o Determine how many bits to borrow o Figure out the new subnet mask o Creating subnet ID o Figure out host IDs for each subnet

The NIC physical address

• Unique 48 binary bit MAC address > converted into 12 hex digits • Divided the 12 hex digits into 2 groups o First six digits: vendor ID or OUI (first six hex digits) is assigned by IEEE o Last six digits: added in the factory 00-1B-77-85-55-DE First three OUI, last three factory assigned Organizationally unique identifier For each OUI, addresses to create 16^6 or 2^24 $1200 to get OUI