It and Computer Science part 2
Interface
The place at which independent and often unrelated systems meet and act on or communicate with each other.
WAN (Wide Area Network)
A network that spans a long distance and connects two or more LANs.
Although a MAC address is typically written using hexadecimal notation, how many binary bits are contained in a MAC address?
48 A MAC address contains 48 bits. The first 24 bits identify a vendor, and the remaining 24 bits are assigned by the vendor.
Consider the topology where Server 1, inside a corporate network, is learning time from an Internet-based NTP server. After learning time from the Internet, Server 1 can use NTP to provide time to devices in the corporate network. What will be the Stratum value of Server 1?
5
How many channels of separation should you have in a 2.4 GHz wireless network to avoid overlapping frequencies?
5
You're examining the output of the ipconfig command issued on an Apple Mac running MacOS, which shows IP address information for the computer. You notice that this computer has an IPv6 address of 2600:1700:35f0:7640:1034:3f5b:9812:ddb3 and a prefix length of 64 bits. The output is shown in the graphic. Based on this information, how many bits are used to identify a host on this network?
64 An IPv6 address is 128 bits in length. The output tells us that the prefix length is 64 bits. That means the portion of the address representing the network is 64 bits in length, and the remaining bits are host bits. Therefore, the number of hosts bits = 128 bits - 64 bits = 64 bits.
What port number is used by HTTP?
80 HTTP uses TCP port 80.
CAN (Campus Area Network)
A network that covers an area equivalent to an academic campus or business park. Can connect near by buildings.
LAN (Local Area Network)
A connection of two or more computers in close proximity.
DHCP (Dynamic Host Configuration Protocol)
A network service that provides automatic assignment of IP addresses and other TCP /IP configuration information.
PAN (Personal Area Network)
A network that connects two to three workstations with twisted pair cabling most often seen in small or home offices.
MAN (Metropolitan Area Network)
A network that covers an area equivalent to a city or other municipality.
DHCP relay agent
A service that captures a BOOTP broadcast and forwards it through the router as a unicast transmission to a DHCP server on a remote subnet.
QoS (Quality of Service)
A set of parameters that controls the level of quality provided to different types of network traffic.
NAT (Network Address Translation)
A technique often used to conserve IP addresses by maps devices on a private network to single Internet-connected device that acts on their behalf.
Shielded Twisted Pair (STP)
A twisted pair cable that has an aluminum shield inside the plastic jacket that surrounds the pairs of wires.
Media Acess Control (MAC) address
A unique identifier assigned to network adapters by the manufacturer. This address is six octets in length and is written in hexadecimal.
What is the sequence of messages exchanged when a network client obtains IP address information using DHCP?
Discover, Offer, Request, Acknowledgement
Wired connection
Actual wires and cables connecting computers (mostly telephone lines and undersea cables).
NTP (Network Time Protocol)
An Internet protocol that enables synchronization of computer clock times in a network of computers by exchanging time signals. MAX is 16, otherwise you are too far off.
What network service translates names into corresponding IP addresses?
DNS
The image shows the seven layers of the OSI Model. Which layer is concerned with physical addressing?
Data Link The Data Link layer (i.e. Layer 2) is concerned with physical addressing. For example, an Ethernet switch learns Layer 2 MAC addresses. Therefore, an Ethernet switch is considered to be a Data Link layer device.
Hypertext Transfer Protocol (HTTP)
How data is transferred through the servers.
In a NAT configuration, what name is given to the private IP address inside a network?
Inside Local
Logical address (IP)
Is a personal address
What contains the circuitry required for a client to connect to a network?
NIC A Network Interface Card (NIC) can be external or internal to a network client, and it provides the circuitry required for that client to connect into a network, either via a wired or wireless connection.
Unshielded Twisted Pair (UTP)
Networking cable that has four twisted pairs of copper wire and a flexible outer coating.
What is the name of the protocol data unit (PDU) routed by routers?
Packet The name given to data at Layer 3, which is where a router resides, is packets.
UDP (User Datagram Protocol)
Protocol that operates instead of TCP in applications where delivery speed is important and quality can be sacrificed.
A router interface's buffer is also known as
Queue
The process of a wireless client attaching to an access point (AP) with the strongest signal as the client moves around a wireless coverage area is called what?
Roaming The term "roaming" refers to a wireless client moving from one physical location to another and seamlessly switching to another wireless access point, which offers a stronger signal in that location.
What type of fiber optic cabling is typically used for long distance applications?
Single-mode fiber optic cabling is typically used for long distance applications, because it does not suffer from multi-mode delay distortion, which results in bits arriving out of order due to multiple paths of propagation (i.e. modes).
IPv4
The Internet Protocol version 4 is the dominant protocol for routing traffic on the Internet, specifying "to" and "from" addresses using a dotted decimal such as "122.45.255.0". It has 32 bits in length.
IPv6
The Internet Protocol version 6 provides a large number of new addresses to route Internet traffic, using "from" and "to" addresses written as colon-hexadecimal notation, such as "fe80::42:acff:feaa:1bf0". It has 128 bits in length
DNS (Domain Name System)
The Internet's system for converting alphabetic names into numeric IP addresses.
TCP
Transmission Control Protocol - provides reliable, ordered, and error-checked delivery of a stream of packets on the internet. TCP is tightly linked with IP and usually seen as TCP/IP in writing.
TCP/IP
Transmission Control Protocol/Internet Protocol
TCP and UDP reside at what layer of the OSI Model?
Transport TCP and UDP reside at the Transport Layer of the OSI Model, which is also known as Layer 4.
In the topology shown, PC A is obtaining IP address information from the Server through an exchange of Discover, Offer, Request, and Acknowledgement messages. If you were to examine one of the packets in this exchange, what port number would be used by the packet?
UDP Port 67 Obtaining IP address information from a server through an exchange of Discover, Offer, Request, and Acknowledgement messages is a function of Dynamic Host Configuration Protocol (DHCP). DHCP uses UDP port 67.
A Layer 2 Ethernet switch constructs a MAC address table. What information is contained in this table?
a mapping of MAC addresses to the ports off of which they were learned
VPN (Virtual Private Network)
a network that uses a public telecommunication infrastructure, such as the Internet, to provide remote offices or individual users with secure access to their organization's network
Open Systems Interconnection (OSI) model
a seven-layer architecture for defining how data is transmitted from computer to computer in a network, from the physical connection to the network to the applications that users run. It also standardizes interactions between network computers exchanging information.
Mesh (wireless)
ad hoc devices work together to form a mesh "cloud" self form and self heal
Dynamic Host Configuration Protocol (DHCP)
allows dynamic IP address allocation so users do not have to have a preconfigured IP address to use the network
Hypertext Transfer Protocol Secure (HTTPS)
an encrypted form of information transfer on the Internet that combines HTTP and TLS
Wireless connection
connects computers without the use of cables or wires Cellular service data Wireless LAN via Wi-fi
You performed a packet capture of traffic on the network. The packet highlighted in the graphic came from a network interface card (NIC) manufactured by Samsung, and it has a MAC address of d0:03:df:89:52:fc. What portion of the MAC address identified the NIC manufacturer as Samsung?
d0:03:df
In the topology shown, PC A is learning the first 64 bits of its address from router R1, and it's self-generating the last 64 bits of its address, using EUI-64. It learns other address information (e.g. the address of a DNS server) from a DHCP server. What type of DHCP is being used in this scenario?
stateless DHCPv6 PC A's total address size is 128 bits (64 bits learned from R1 and 64 bits self-generated using EUI-64). Therefore, it's using IPv6. Since it didn't learn all of it's IP address information from a DHCPv6 server, the type of DHCPv6 being used is stateless DHCPv6.
What NTP parameter indicates the believability of a network time source?
stratum value NTP uses stratum values to determine the believability of a network time source, where lower stratum values are more believable than higher stratum values.
In an IPv4 address, what is used to identify the network and host portions of the address?
subnet mask A subnet mask is a series of 32 bits and is used to identify the network and host portions of an IPv4 address.
Internet of Things (IoT)
the network of products embedded with connectivity-enabled electronics
Ad hoc wireless network
two or more devices connected together without an AP
