Modules 5-10 Flashcards
allows computers in a home office or a remote office to connect to a corporate network, or access centralized, shared resources.
Small Office and Home Office Networks
connect a few computers to each other and to the internet.
Small Home Networks
The internet is a network of networks that connects hundreds of millions of computers world-wide.
World Wide Networks
All computers that are connected to a network and that participate directly in network communication are classified as
Hosts
such as those used by corporations and schools, can have many locations with hundreds or thousands of interconnected hosts.
Medium to Large Networks
stores corporate and user files in a central location.
File Server
runs ___ ________ software that allows many computers to access web pages.
Web Server
runs email server software that enables emails to be sent and received.
Email Server
This means it is freely available to the public and can be used by any vendor on their hardware or in their software.
Open standard protocol suite
This means it has been endorsed by the networking industry and approved by a standards organization. This ensures that products from different manufacturers can interoperate successfully.
Standards-based protocol suite
Protocols under Application Layer
Application Layer
Name System
DNS - Domain Name System.
Host Config:
DHCPv4 - Dynamic Host Configuration Protocol for IPv4.
DHCPv6 - Dynamic Host Configuration Protocol for IPv6.
SLAAC - Stateless Address Autoconfiguration.
Email:
SMTP - Simple Mail Transfer Protocol.
POP3 - Post Office Protocol version 3.
IMAP - Internet Message Access Protocol.
File Transfer:
FTP - File Transfer Protocol.
SFTP - SSH File Transfer Protocol.
TFTP - Trivial File Transfer Protocol.
Web and Web Service:
HTTP - Hypertext Transfer Protocol.
HTTPS - HTTP Secure.
REST - Representational State Transfer.
Protocols Under Transport Layer
Transport layer
Connection-Oriented:
TCP - Transmission Control Protocol.
Connectionless:
UDP - User Datagram Protocol.
Protocols Under Internet Layer
Internet Layer
Internet Protocol
IPv4 - Internet Protocol version 4.
IPv6 - IP version 6.
NAT - Network Address Translation.
Messaging:
ICMPv4 - Internet Control Message Protocol for IPv4.
ICMPv6 - Internet Control Message Protocol for IPv6.
ICMPv6 ND - Internet Control Message Protocol for IPv6 Neighbor Discovery.
Routing Protocols:
OSPF - Open Shortest Path First.
EIGRP - EIGRP - Enhanced Interior Gateway Routing Protocol.
BGP - Border Gateway Protocol.
Protocols Under Network Access Layer
Network Access Layer
Address Resolution:
ARP - Address Resolution Protocol.
Data Link Protocols:
Ethernet
WLAN - Wireless Local Area Network.
Translates domain names such as cisco.com, into IP addresses.
DNS (Domain Name System)
________ server dynamically assigns IPv4 addressing information to DHCPv4 clients at start-up and allows the addresses to be re-used when no longer needed.
DHCPv4 - Dynamic Host Configuration Protocol for IPv4
is similar to DHCPv4. A ______ server dynamically assigns IPv6 addressing information to ______ clients at start-up.
DHCPv6 - Dynamic Host Configuration Protocol for IPv6
A method that allows a device to obtain its IPv6 addressing information without using a DHCPv6 server.
SLAAC - Stateless Address Autoconfiguration
Enables clients to send email to a mail server and enables servers to send email to other servers.
SMTP - Simple Mail Transfer Protocol
Enables clients to retrieve email from a mail server and download the email to the client’s local mail application.
POP3 - Post Office Protocol version 3
Enables clients to access email stored on a mail server as well as maintaining email on the server.
IMAP - Internet Message Access Protocol
Sets the rules that enable a user on one host to access and transfer files to and from another host over a network. ___ is a reliable, connection-oriented, and acknowledged file delivery protocol.
FTP - File Transfer Protocol
A simple, connectionless file transfer protocol with best-effort, unacknowledged file delivery. It uses less overhead than FTP.
TFTP - Trivial File Transfer Protocol
As an extension to Secure Shell (SSH) protocol, SFTP can be used to establish a secure file transfer session in which the file transfer is encrypted. SSH is a method for secure remote login that is typically used for accessing the command line of a device.
SFTP - SSH File Transfer Protocol
A set of rules for exchanging text, graphic images, sound, video, and other multimedia files on the World Wide Web.
HTTP - Hypertext Transfer Protocol
A web service that uses application programming interfaces (APIs) and HTTP requests to create web applications.
REST - Representational State Transfer
A secure form of HTTP that encrypts the data that is exchanged over the World Wide Web.
HTTPS - HTTP Secure
Enables reliable communication between processes running on separate hosts and provides reliable, acknowledged transmissions that confirm successful delivery.
TCP - Transmission Control Protocol
Enables a process running on one host to send packets to a process running on another host. However, ___ does not confirm successful datagram transmission.
UDP - User Datagram Protocol
Similar to IPv4 but uses a 128-bit address.
IPv6 - IP version 6
Provides feedback from a destination host to a source host about errors in packet delivery.
ICMPv4 - Internet Control Message Protocol for IPv4
Receives message segments from the transport layer, packages messages into packets, and addresses packets for end-to-end delivery over a network. ____uses a 32-bit address.
IPv4 - Internet Protocol version 4
Similar functionality to ICMPv4 but is used for IPv6 packets.
ICMPv6 - ICMP for IPv6
ink-state routing protocol that uses a hierarchical design based on areas. ____ is an open standard interior routing protocol.
OSPF - Open Shortest Path First
Includes four protocol messages that are used for address resolution and duplicate address detection.
ICMPv6 ND - ICMPv6 Neighbor Discovery
An open standard routing protocol developed by Cisco that uses a composite metric based on bandwidth, delay, load and reliability.
EIGRP - Enhanced Interior Gateway Routing Protocol
Provides dynamic address mapping between an IPv4 address and a hardware address.
ARP - Address Resolution Protocol
An open standard exterior gateway routing protocol used between Internet Service Providers (ISPs). ___ is also commonly used between ISPs and their large private clients to exchange routing information.
BGP - Border Gateway Protocol
Defines the rules for wiring and signaling standards of the network access layer.
Ethernet
Defines the rules for wireless signaling across the 2.4 GHz and 5 GHz radio frequencies.
WLAN - Wireless Local Area Network
This is the process of managing the rate of data transmission. Flow control defines how much information can be sent and the speed at which it can be delivered. For example, if one person speaks too quickly, it may be difficult for the receiver to hear and understand the message. In network communication, there are network protocols used by the source and destination devices to negotiate and manage the flow of information.
Flow Control
A one-to-one delivery option is referred to as a _______, meaning there is only a single destination for the message.
Unicast
If a person asks a question and does not hear a response within an acceptable amount of time, the person assumes that no answer is coming and reacts accordingly. The person may repeat the question or instead, may go on with the conversation. Hosts on the network use network protocols that specify how long to wait for responses and what action to take if a response timeout occurs.
Response Timeout
This determines when someone can send a message. Click Play in the figure to see an animation of two people talking at the same time, then a “collision of information” occurs, and it is necessary for the two to back off and start again. Likewise, when a device wants to transmit on a wireless LAN, it is necessary for the WLAN network interface card (NIC) to determine whether the wireless medium is available.
Access method
When a host needs to send messages using a one-to-many delivery option, it is referred to as a _________
Multicast
If all hosts on the network need to receive the message at the same time, a _________ may be used. _________ represents a one-to-all message delivery option.
Broadcast
layer contains protocols used for process-to-process communications.
Application
layer provides for common representation of the data transferred between application layer services.
Presentation
layer provides services to the presentation layer to organize its dialogue and to manage data exchange.
Session
defines services to segment, transfer, and reassemble the data for individual communications between the end devices.
Transport
layer provides services to exchange the individual pieces of data over the network between identified end devices.
Network
layer protocols describe methods for exchanging data frames between devices over a common media
Data Link
layer protocols describe the mechanical, electrical, functional, and procedural means to activate, maintain, and de-activate physical connections for a bit transmission to and from a network device.
Physical
Represents data to the user, plus encoding and dialog control.
Application
Supports communication between various devices across diverse networks.
Transport
Controls the hardware devices and media that make up the network.
Network Access
Determines the best path through the network.
Internet
The minimum and the maximum Ethernet frame size is
64 bytes and 1518 bytes
Any frame less than 64 bytes in length is considered a
Collision Fragment or Runt Frame
Frames with more than 1500 bytes of data are considered
Jumbo or Baby Giant Frames
fields are used for synchronization between the sending and receiving devices. These first eight bytes of the frame are used to get the attention of the receiving nodes. Essentially, the first few bytes tell the receivers to get ready to receive a new frame.
Preamble and Start Frame Delimiter Fields
This 6-byte field is the identifier for the intended recipient. As you will recall, this address is used by Layer 2 to assist devices in determining if a frame is addressed to them. The address in the frame is compared to the MAC address in the device. If there is a match, the device accepts the frame. Can be a unicast, multicast or broadcast address.
Destination MAC Address Field
This 6-byte field identifies the originating NIC or interface of the frame. Can only be a unicast address.
Source MAC Address Field
This 2-byte field identifies the upper layer protocol encapsulated in the Ethernet frame. Common values are, in hexadecimal, 0x800 for IPv4, 0x86DD for IPv6 and 0x806 for ARP.
Type / Length
This field (46 - 1500 bytes) contains the encapsulated data from a higher layer, which is a generic Layer 3 PDU, or more commonly, an IPv4 packet. All frames must be at least 64 bytes long. If a small packet is encapsulated, additional bits called a pad are used to increase the size of the frame to this minimum size.
Data Field
is used to detect errors in a frame. It uses a cyclic redundancy check (CRC). The sending device includes the results of a CRC in the FCS field of the frame. The receiving device receives the frame and generates a CRC to look for errors. If the calculations match, no error occurred. Calculations that do not match are an indication that the data has changed; therefore, the frame is dropped. A change in the data could be the result of a disruption of the electrical signals that represent the bits.
Frame Check Sequence Field
The maximum size of the PDU that each medium can transport is referred to as the
Maximum Transmission Unit (MTU)
Designed to support extremely large networks with more than 16 million host addresses.
Class A(0.0.0.0/8 to 127.0.0.0/8)
Designed to support moderate to large size networks with up to approximately 65,000 host addresses.
Class B(128.0.0.0 /16 – 191.255.0.0 /16)
Designed to support small networks with a maximum of 254 hosts.
Class C(192.0.0.0 /24 – 223.255.255.0 /24)
is the time a packet takes to reach the remote host and for the response from the host to return.
Round Trip Time (RTT)
Configured with a unique IP address for identification
Addressing end devices
Select the best path and direct packets towards destination host.
Routing
IP is inherently unreliable because packet delivery is not guaranteed.
Best Effort
There is no connection with the destination established before sending data packets.
Connectionless
Operation is independent of the medium (for example, copper, fiber-optic, or wireless) carrying the data.
Media Independent
The solution is to reduce the size of the network to create smaller broadcast domains in a process called
subnetting
command can be used to display the host routing table. Both commands generate the same output.
route printor netstat -r
When a device is assigned a global unicast or link-local unicast address, the ___ is performed on the address to ensure that it is unique.
Duplicate Address Detection (DAD)
The message will include a code that indicates why the packet could not be delivered. The Destination Unreachable codes for ICMPv4 includes the following:
0 - Net unreachable
1 - Host unreachable
2 - Protocol unreachable
3 - Port unreachable
is a utility that generates a list of hops that were successfully reached along the path. This list can provide important verification and troubleshooting information.
Traceroute (tracert)
is the time a packet takes to reach the remote host and for the response from the host to return.
Round Trip Time (RTT)
It uses message codes to differentiate between different types of ICMP messages. These are some common message codes:
0 – Echo reply (response to a ping)
3 – Destination Unreachable
5 – Redirect (use another route to the destination)
8 – Echo request (for ping)
11 – Time Exceeded (TTL became 0)
When a packet is sent to the data link layer to be encapsulated into an Ethernet frame, the device refers to a table called
ARP table or ARP cache
A 16-bit field used to identify the source application by port number.
Source Port
command is used to display the ARP table.
Cisco: show ip arp | Windows 10: arp –a
A 32-bit field used for data reassembly purposes.
Sequence Number
A 16-bit field used to identify the destination application by port number.
Destination Port
A 32-bit field used to indicate that data has been received and the next byte expected from the source.
Acknowledgment Number
A 4-bit field known as ʺdata offsetʺ that indicates the length of the TCP segment header.
Header Length
A 6-bit field that is reserved for future use.
Reserved
A 6-bit field that includes bit codes, or flags, which indicate the purpose and function of the TCP segment.
Control bits
A 16-bit field used to indicate the number of bytes that can be accepted at one time.
Window size
A 16-bit field used for error checking of the segment header and data.
Checksum
A 16-bit field used to indicate if the contained data is urgent.
Urgent
Urgent pointer field significant
URG
Acknowledgment flag used in connection establishment and session termination
ACK
Push function
PSH
Reset the connection when an error or timeout occurs
RST
Synchronize sequence numbers used in connection establishment
SYN
No more data from sender and used in session termination
FIN
A destination sending acknowledgments as it processes bytes received, and the continual adjustment of the source send window, is known as
sliding windows
Dynamic Host Configuration Protocol (DHCP) for IPv4 service automates the assignment of IPv4 addresses, subnet masks, gateways, and other IPv4 networking parameters.
Dynamic
The network administrator manually enters IP address information on hosts.
Static
message to identify any available DHCP servers on the network.
DHCPDISCOVER
message, which offers a lease to the client.
DHCPOFFER
that identifies the explicit server and lease offer that the client is accepting.
DHCPREQUEST
If the IPv4 address requested by the client, or offered by the server, is still available, the server returns the _______ message.
DHCPACK
If the offer is no longer valid, then the selected server responds with a
DHCPNAK
If the mapping is not found there, the DNS server will query other higher-level DNS servers that are authoritative for the top-level domain in order to find the mapping. These are known as
recursive queries
The DNS protocol communications use a single format called a
message
The process of transferring DNS data between servers is known as
zone transfer
The question for the server. It contains the domain name to be resolved, the class of domain, and the query type.
Question
The DNS resource record, or RR, for the query including the resolved IP address depending on the RR type.
Answer
Contains the RRs for the domain authority.
Authority
Relevant to query responses only. Consists of RRs that hold additional information that will make query resolution more efficient
Additional
is a TCP-based protocol that is used to identify the owners of internet domains through the DNS system.
WHOIS
NAT-enabled routers can be configured with one or more valid public IPv4 addresses which are known as the
NAT pool
