1. Introduction To Networking

The Data Link Layer

Question 1

How many octets are there in a MAC address?

  • 5
  • 8
  • 4
  • 6

A MAC address is a 48-bit number consisting of 6 octets.

Question 2

What address is used for Ethernet broadcasts?

  • 00:00:00:00:00:00
  • 11:11:11:11:11:11
  • FF:FF:FF:FF:FF:FF
  • FF:00:FF:00:FF:00

The address FF:FF:FF:FF:FF:FF is used for Ethernet broadcast traffic.

Question 3

What is a cyclical redundancy check?

  • A technique that allows for multiple logical LANs to operate on the same equipment
  • The actual data being transported by an Ethernet frame
  • A way for two computers to synchronize their clocks
  • A mathematical calculation used to ensure that all data arrived intact

A cyclical redundancy check ensures that there was no data corruption.

Networking Devices

Question 1

Which of the following statements accurately describe the differences between a hub and a switch? Check all that apply.

  • A hub is a physical layer device, and a switch is a data link layer device.
  • A hub causes larger collision domains.
  • A switch remembers which devices are connected on each interface, while a hub does not.
  • Hubs are more sophisticated versions of switches.

Question 2

What does LAN stand for?

  • Locally available network
  • Local area network
  • Little area network
  • Large area network

LAN stands for Local Area Network.

Question 3

What’s a router?

  • A network device used specially for fiber cables
  • A more advanced version of a switch
  • A device that knows how to forward data between independent networks
  • A physical layer device that prevents crosstalk

A router connects independent networks by forwarding data between them.

TCP/IP

Question 1

Which of the following is an example of a network layer (layer 3) protocol?

  • Ethernet
  • IP
  • UDP
  • TCP

IP, or Internet Protocol, is the most common network layer protocol.

Question 2

What’s the difference between a client and a server?

  • Clients and servers are different names for the same thing.
  • A server requests data, and a client responds to that request.
  • Clients operate on the data link layer, and servers operate on the network layer.
  • A client requests data, and a server responds to that request.

Question 3

Which of the following are examples of layers of our five-layer network model? Check all that apply.

  • The physical layer
  • The application layer
  • The presentation layer
  • The transport layer

The Data Link Layer

Question 1

How many octets are there in a MAC address?

  • 5
  • 8
  • 4
  • 6

A MAC address is a 48-bit number consisting of 6 octets.

Question 2

What address is used for Ethernet broadcasts?

  • 00:00:00:00:00:00
  • 11:11:11:11:11:11
  • FF:FF:FF:FF:FF:FF
  • FF:00:FF:00:FF:00

The address FF:FF:FF:FF:FF:FF is used for Ethernet broadcast traffic.

Question 3

What is a cyclical redundancy check?

  • A technique that allows for multiple logical LANs to operate on the same equipment
  • The actual data being transported by an Ethernet frame
  • A way for two computers to synchronize their clocks
  • A mathematical calculation used to ensure that all data arrived intact

A cyclical redundancy check ensures that there was no data corruption.

The Physical Layer

Question 1

What is the type of modulation used by twisted pair cable computer networks known as?

  • Line crimping
  • Simplex communication
  • Line coding
  • RJ45

Line coding is the modulation of an electrical charge so that each side of a connection knows what is a one and what is a zero.

Question 2

What’s the difference between full and half duplex?

  • Full duplex is slower than half duplex.
  • Full duplex allows communications in two directions at the same time; half duplex means that only one side can communicate at a time.
  • Full duplex is a form of simplex communications.
  • Half duplex occurs when hubs are in use; full duplex occurs when switches are in use.

A half duplex connection allows communication in both directions, but only one side can communicate at a time.

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2. The Network Layer

Routing

Question 1

Select examples of routing protocols. Check all that apply.

  • Border Gateway Protocol
  • Routing Information Protocol
  • Transmission Control Protocol
  • Hypertext Transfer Protocol
  • User Datagram Protocol

Question 2

Who is permitted to use non-routable address space?

  • Anyone
  • The IANA
  • It’s for testing purposes only
  • The IETF

Anyone can use non-routable address space.

Question 3

A typical routing table may contain which of the following? Check all that apply.

  • Destination address
  • Total hops
  • Destination network
  • TTL

Subnetting

Question 1

What does CIDR stand for?

  • Classless Internet Destination Routing
  • Classfull Inter-Destination Routing
  • Classless Inter-Domain Routing
  • Classfull Identification Routing

CIDR stands for Classless Inter-Domain Routing.

Question 2

Which of the following is a correct form of CIDR notation?

  • 192.168.1.0:24
  • 192.168.1.0/24
  • 192.168.1.0\24
  • 192.168.1.0 + 255.255.255.0

CIDR notation uses a forward slash and then lists the numbers of bits in the subnet mask.

Question 3

How many octets does a subnet mask have?

  • 1
  • 2
  • 3
  • 4

A subnet mask is the same length as an IP address.

The Network Layer

Question 1

Please select all of the valid IP addresses. Check all that apply.

  • 123.456.123.456
  • 192.168.1.1
  • 8.8.8.8
  • 257.70.312.49

Question 2

What happens to the TTL field of an IP datagram every time it reaches a router?

  • The TTL field is decremented by one.
  • The TTL field is reset to zero.
  • The TTL field is used for a cyclical redundancy check.
  • The TTL field is incremented by one.

At every router hop, the TTL field is decremented by one until it reaches zero, causing the datagram to be discarded.

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3. The Transport & Application Layer

The Application Layer

Question 1

Unlike our five-layer model, the OSI network model adds two more layers on top of the Application Layer. Select examples of these new layers below.

  • The interconnection layer
  • The encryption layer
  • The presentation layer
  • The session layer
  • The compression layer

Question 2

An example of something that operates at the application layer is:

  • A router
  • TCP
  • A web browser
  • UDP

Web browsers and server operate at the application layer.

Question 3

What’s the standard number for a TTL field?

8
16
32
64

While this value can be set to anything from 0 to 255, 64 is the recommended standard.

The Transport Layer

Question 1

What ordering of TCP flags makes up the Three-way Handshake?

  • FIN, FIN/ACK, ACK
  • SYN, SYN/ACK, ACK
  • SYN, ACK, SYN, ACK
  • SYN, ACK, FIN

The computer that wants to establish a connection sends a packet with the SYN flag set. Then, the server responds with a packet with both the SYN and ACK flags set. Finally, the original computer sends a packet with just the ACK flag set.

Question 2

Transport layer protocols, like TCP and UDP, introduce the concept of a port. How many bits is a port field?

  • 4 bits
  • 8 bits
  • 16 bits
  • 32 bits

A TCP or UDP port is a 16-bit number, meaning there are theoretically 65,535 possible values it can have.

Question 3

Please select all valid TCP control flags.

  • WAIT
  • LISTEN
  • CLOSE
  • ACK
  • RST
  • URG

Question 4

A device that blocks traffic that meets certain criteria is known as a __.

  • Firewall
  • Router
  • Switch
  • Hub

A firewall is used to block certain defined types of traffic.

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4. Network Services

Dynamic Host Configuration Protocol

Question 1

What are the four things that all computers need configured in order to operate on a modern network? Check all that apply.

  • An NTP server
  • A TCP port
  • A name server
  • An IP address
  • A default gateway
  • A subnet mask
  • A MAC address

Question 2

When using Fixed Allocation DHCP, what’s used to determine a computer’s IP?

  • A record
  • Location
  • A MAC address
  • A subnet mask

Fixed Allocation DHCP ensures that computers receive an IP address reserved for it via its MAC address.

Question 3

The process by which a client configured to use DHCP attempts to get network configuration information is known as _____.

  • DHCP Discovery
  • DHCP Request
  • DHCP Offer
  • DHCP Acknowledgement

DHCP Discovery is how a client determines configuration information.

Name Resolution in Practice

Question 1

An A Record contains what?

  • A CNAME
  • An IPv4 address
  • An IPv6 address
  • A fully qualified domain name

Question 2

Select all that are true.

  • One domain name can point to one IP.
  • One domain name can point to many IPs.
  • Many domain names can point to the same IP.

Question 3

MX stands for __.

  • Micro extreme
  • Micro exchange
  • Mail exchange
  • Meta exchange

MX stands for mail exchange.

Question 4

A fully qualified domain name can contain how many characters?

  • 63
  • 64
  • 127
  • 255

An FQDN is limited to a total length of 255 characters.

Name Resolution

Question 1

What transport layer protocol does DNS normally use?

  • TCP
  • IP
  • ICMP
  • UDP

While DNS over TCP does exist, UDP is the most common protocol.

Question 2

A DNS TTL determines what?

  • How many steps there are in the resolution process
  • How far away a DNS can be from you
  • How many DNS resolutions can take place before the IP has to change
  • How long a DNS entry is allowed to be cached

TTL stands for Time to Live and determines how long a DNS entry can be cached.

Question 3

How many root servers are there?

  • 8
  • 13
  • 16
  • 17

There are 13 root servers.

Network Address Translation

Question 1

NAT addresses concerns over the dwindling IPv4 address space by _______.

  • allowing networks to use fewer IP addresses overall.
  • allowing users to move to IPv6 when they want.
  • allowing computers using non-routable address space to communicate with the Internet.
  • performing IP masquerading.

NAT allows networks to use non-routable address space for their internal devices.

Question 2

What technique allows for inbound traffic through a NAT?

  • Port preservation
  • Port forwarding
  • Port authority
  • Ephemeral ports

Port forwarding is a technique that allows for inbound traffic through a router configured to NAT.

Question 3

The total number of IPv4 addresses is approximately:

  • 4.2 million
  • 4.2 billion
  • 4.2 trillion
  • Uncountable

There are approximately 4.2 billion IPv4 addresses.

VPNs & Proxies

Question 1

Two-factor authentication is_________________________.

  • a method where you need two passwords.
  • a method that requires two usernames.
  • a method where you authenticate twice.
  • a method where you need more than a username and a password.

Two-factor authentication requires a username/password and something extra.

Question 2

VPNs are known as a _ protocol.

  • connectionless
  • data link layer
  • tunneling
  • network layer

VPNs are tunneling protocols.

Question 3

A proxy is something that ___________.

  • sends data across a single network segment.
  • communicates on behalf of something else.
  • encrypts traffic sent across the Internet.
  • allows for many devices to speak to one other device.

While proxies are many things, they primarily communicate on behalf of something else.

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5. Connecting To The Internet

Broadband Internet

Question 1

T1 is short for __.

  • Transportation System 1.
  • Transmission System 1.
  • Transportation 1.
  • Transmission 1.

T1 is short for Transmission System 1.

Question 2

How fast is a T1 line?

  • 1.544 Mb/sec
  • 44.763 Mb/sec
  • 1 Mb/sec
  • 128 Mb/sec

A T1 communicates at speeds of 1.544 Kb/sec.

Question 3

Select all statements that are true of cable internet connections.

  • They’re broadband connections.
  • They’re dial-up connections.
  • They’re shared bandwidth connections.
  • They’re wireless connections.

POTS and Dial-up

Question 1

Another term for POTS, or the Plain Old Telephone System, is ___.

  • Public Switched Telephone Network.
  • Phone Switched Transport Network.
  • Public Switched Telephone Exchange.
  • Public Available Telephone Network.
  • Public Available Telephone Exchange.

POTS and PSTN refer to the same thing.

Question 2

A baud rate is a measurement of the number of __________.

  • data segments that can be sent across a telephone line every second.
  • bits that can be sent across a telephone line every second.
  • bytes that can be sent across a telephone line every second.
  • packets that can be sent across a telephone line every second.

A baud rate is equivalent to bits per second.

WANs

Question 1

WAN stands for __.

  • Wide Area Network.
  • Wired Area Network.
  • Wireless Area Network.
  • Wireless Local Area Network.

WAN stands for Wide Area Network.

Question 2

In a WAN, the area between a demarcation point and the ISP’s core network is known as _.

  • an access point
  • a local loop
  • a Local Area Network
  • a local link

A local loop is the name for the area between a demarcation point and an ISP’s network.

Question 3

A point-to-point VPN is also known as a __.

  • site-to-site VPN
  • one-to-many VPN
  • port forwarding VPN
  • data link VPN

A point-to-point VPN can also be referred to as a site-to-site VPN.

Wireless Networking

Question 1

How many address fields does an 802.11 header have?

  • 1
  • 2
  • 3
  • 4

There are four different address fields in an 802.11 header.

Question 2

A wireless channel is __.

  • a portion of a frequency band.
  • a point-to-point wireless connection.
  • a collision domain.
  • an example of an ad-hoc network.

A channel represents a portion of a frequency band.

Question 3

Choose all of the frequencies that wireless networks typically operate on.

  • 88Mhz
  • 1.544Ghz
  • 2.4Ghz
  • 5Ghz

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6. Trouble the Future of The Internet

Digging into DNS

Question 1

One of Level 3’s public DNS servers is __.

  • 4.2.2.3
  • 8.8.8.8
  • 127.0.0.1
  • 192.168.1.1

Level 3’s public DNS servers are 4.2.2.1 through 4.2.2.6

Question 2

A DNS resolver tool available on all major desktop operating systems is __.

  • host
  • tracert
  • ping
  • nslookup

nslookup is available by default on Windows, macOS, and Linux.

Question 3

The organization responsible for DNS at a global level is __.

  • Google
  • RFC
  • ICANN
  • IANA

ICANN is responsible for DNS at a global level.

IPv6

Question 1

An IPv6 address is how many bits long?

  • 16
  • 32
  • 64
  • 128

An IPv6 address is 128 bits long

Question 2

The very first field in an IPv6 header is the _.

  • data payload field
  • version field
  • source address field
  • traffic class field

This field is used to indicate what version of IP is being used.

Question 3

The IPv6 header field that indicates how many routers can forward a packet before it’s discarded is called the __.

  • next header field
  • router forward field
  • hop limit field
  • TTL

The hop limit field configures how many routers can try to forward a packet before it’s discarded.

The Cloud

Question 1

A piece of software that runs and manages virtual machines is known as a __.

  • cloud storage device
  • hypervisor
  • cloud computing device
  • virtual instance

A hypervisor manages many virtual instances running on a single host.

Question 2

Office 365 Outlook is an example of _.

  • IaaS
  • PaaS
  • FttH
  • SaaS

Office 365 Outlook is an example of Software as a Service (SaaS).

Question 3

A hybrid cloud is ____.

  • a combination of virtual hosts and virtual guests
  • a combination of a public cloud and a private cloud
  • a combination of a public cloud and hardware virtualization
  • a combination of a private cloud and a mesh network

A hybrid cloud runs some services on a cloud provider and some services in-house.

Verifying Connectivity

Question 1

The protocol used to communicate network errors is known as __.

  • Traceroute
  • UDP
  • ICMP
  • TCP

ICMP is used to communicate errors back to the client.

Question 2

The ping utility sends what message type?

  • Destination Network Unknown
  • Destination Network Unreachable
  • Echo Request
  • Echo Reply

By default, the ping utility sends an Echo Request ICMP message type.

Question 3

On Windows, one of the tools you can use to verify connectivity to a specific port is __.

  • nc (netcat)
  • Test-NetConnection
  • tracert
  • ping

Test-NetConnection lets you test many things, including connectivity to a specific port on a remote host.

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