CCC NET 125 Chapter 10
internet message access protocol - IMAP
Protocol that describes a method to retrieve email messages. Unlike POP, copies of the messages are downloaded to the client application but the original messages are kept on the server until manually deleted.
bootstrap protocol - BOOTP
Protocol used by a network node to determine the IP address of its Ethernet interfaces, in order to facilitate network booting.
Domain Name System or Service - TCP, UDP port 53
Translates domain names, such as cisco.com, into IP addresses.
Dynamic Host Configuration Protocol - UDP client 68, server 67
Dynamically assigns IP addresses to client stations at start-up. Allows the addresses to be re-used when no longer needed.
store-and-forward
Email is a _________________________________ method of sending, storing, and retrieving electronic messages across a network.
Simple Mail Transfer Protocol - SMTP, Post Office Protocol - POP, and Internet Message Access Protocol - IMAP.
Email supports three separate protocols for operation. These are:
Bootstrap Protocol - UDP client 68, server 67
Enables a diskless workstation to discover its own IP address, the IP address of a BOOTP server on the network, and a file to be loaded into memory to boot the machine. It is being superseded by DHCP.
Internet Message Access Protocol - TCP 143
Enables clients to access email stored on a mail server. Maintains email on the server.
Post Office Protocol - TCP 110
Enables clients to retrieve email from a mail server. Downloads email from the mail server to the desktop.
Simple Mail Transfer Protocol - TCP 25
Enables clients to send email to a mail server. Enables servers to send email to other servers.
request/response
HTTP is a _______________/_______________ protocol.
The data stream is encrypted with Secure Socket Layer - SSL - before being transported across the network.
HTTPS uses the same client request-server response process as HTTP. How is the data stream encrypted before being transported across the network?
http - the protocol or scheme www.cisco.com - the server name index.html - the specific filename requested
How does a browser interpret the three parts of the URL?
The domain name system - DNS, provides domain name to address resolution for networks allowing end users to access resources with names rather than more difficult to remember IP addresses. This automated service matches resource name with the required numeric network addresses.
What is the purpose of DNS?
FTP was developed to allow for data transfers between a client and a server. An FTP client is an application that runs on a computer that is used to push and pull data from a server running an FTP daemon (FTPd).
What is the purpose of FTP?
IMAP is another protocol that describes a method to retrieve email messages.
What is the purpose of Internet Message Access Protocol (IMAP)?
POP is used by an application to retrieve mail from a mail server. With POP, mail is downloaded from the server to the client and then deleted on the server.
What is the purpose of Post Office Protocol (POP)?
To transfer mail reliably and efficiently.
What is the purpose of SMTP?
The DNS protocol defines an automated service that matches resource names with the required numeric network address.
What is the purpose of a Domain Name System (DNS)?
It is the layer that provides the interface between the applications used to communicate and the underlying network over which our messages are transmitted. Application layer protocols are used to exchange data between programs running on the source and destination hosts.
What is the purpose of the application layer?
The network includes a dedicated server.
What is true about a client-server network?
Email supports three separate protocols for operation: simple mail transfer protocol - SMTP, post office protocol - POP, and internet message access protocol - IMAP.
What main protocols do email users and servers normally use to process email?
Port 110.
What port number does POP use?
Well-known port 25 or port 587.
What port number does SMTP use?
The Dynamic Host Configuration Protocol (DHCP) for IPv4 service automates the assignment of IPv4 addresses, subnet masks, gateways, and other IPv4 networking parameters.
What services does a DHCP Server offer?
The domain name mapped to mail exchange servers.
What type of information is contained in a DNS MX record?
Hypertext Transfer Protocol Secure - TCP, UDP 443
The browser uses encryption to secure HTTP communications. Authenticates the website to which you are connecting your browser.
daemon
A computer program that runs in the background and is usually initiated as a process. These often support server processes.
client-server
A computer system setup in which tasks are distributed between a service provider (server) and a service user, such as a workstation (client). The server is used to store the applications and data and the majority of the computer processing is done on the server.
Trivia File Transfer Protocol - UDP 69
A simple, connectionless file transfer protocol. A best-effort, unacknowledged file delivery protocol. Utilizes less overhead than FTP.
POP or IMAP.
Clients only use two application layer protocols to retrieve email. These are:
nslookup allows the user to manually query the name servers to resolve a given host name.
Computer operating systems have a utility called nslookup. What does this allow users to do?
DHCP allows a host to obtain an IP address dynamically when it connects to the network.
DHCP enables clients on a network to do what?
Telnet
A non-secure network service that supports CLI access to a remote host. It also can be used to verify the application layer software between source and destination stations.
client, server
A peer-to-peer (P2P) application allows a device to act as both a _______________ and a _______________ within the same communication.
post office protocol - POP
A protocol that allows a computer to retrieve email from a server.
nslookup
A service or a program to look up information in the DNS.
DNS server default gateway
A user is attempting to access http://www.cisco.com/ without success. Which two configuration values must be set on the host to allow this access?
peer-to-peer (P2P)
A wired laser printer is attached to a home computer. That printer has been shared so that other computers on the home network can also use the printer. What networking model is in use?
simple mail transfer protocol - SMTP
An application layer protocol providing electronic mail services to transfer mail from client to server and between servers.
server message block - SMB
An application level network protocol mainly applied to shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network.
Email clients communicate with mail servers to send and receive email. Mail servers communicate with other mail servers to transport messages from one domain to another. An email client does not communicate directly with another email client when sending email. Instead, both clients rely on the mail server to transport messages.
An email client does not communicate directly with another email client when sending email. Explain what happens.
file transfer protocol - FTP
Application protocol, part of the TCP/IP protocol stack, used for transferring files between network nodes. Defined in RFC 959.
application layer
At what layer of the OSI model are the client and server processes are considered to be in?
When an IPv4, DHCP-configured device boots up or connects to the network, the client broadcasts a DHCP discover (DHCPDISCOVER) message to identify any available DHCP servers on the network. A DHCP server replies with a DHCP offer (DHCPOFFER) message, which offers a lease to the client. The offer message contains the IPv4 address and subnet mask to be assigned, the IPv4 address of the DNS server, and the IPv4 address of the default gateway. The lease offer also includes the duration of the lease.
Explain how DHCP operates.
Unlike POP, when the user connects to an IMAP-capable server, copies of the messages are downloaded to the client application. The original messages are kept on the server until manually deleted. Users view copies of the messages in their email client software.
Explain in detail how is IMAP different from POP?
The session layer handles the exchange of information to initiate dialogs, keep them active, and to restart sessions that are disrupted or idle for a long period of time.
Explain in detail the function of the session layer.
The Server Message Block (SMB) is a client/server file sharing protocol that describes the structure of shared network resources, such as directories, files, printers, and serial ports. It is a request-response protocol. All SMB messages share a common format. This format uses a fixed-sized header, followed by a variable-sized parameter and data component.
Explain what is a Server Message Block (SMB)?
DHCP can pose a security risk because any device connected to the network can receive an address. This risk makes physical security a determining factor of whether to use dynamic or manual addressing.
How is DHCP a security risk?
True
In FTP transactions, an FTP client uses the pull method to download files from an FTP server.
client, server
In the client-server model, the device requesting the information is called a _______________ and the device responding to the request is called a _______________.
peer-to-peer - P2P
In this kind of networking, each device serves as both a client and a server portion of an application. It also describes a small local network where hosts can play the role of client and/or server.
Although HTTP is remarkably flexible, it is not a secure protocol. The request messages send information to the server in plain text that can be intercepted and read. The server responses, typically HTML pages, are also unencrypted.
Is HTTP a secure protocol?
GET - A client request for data. A client (web browser) sends the GET message to the web server to request HTML pages. POST - Uploads data files to the web server such as form data. PUT - Uploads resources or content to the web server such as an image.
List and explain the three common message types used by HTTP:
Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), Internet Message Access Protocol (IMAP), and Domain Name System (DNS) protocol.
List the common protocols that fall under the application Layer.
Some well-known standards for video include QuickTime and Motion Picture Experts Group (MPEG). Some well-known graphic image formats that are used on networks are Graphics Interchange Format (GIF), Joint Photographic Experts Group (JPEG), and Portable Network Graphics (PNG) format.
List the common protocols that work in the presentation layer.
Domain Name System - DNS Telnet Secure Shell - SSH Simple Mail Transfer Protocol - SMTP Dynamic Host Configuration Protocol - DHCP Hypertext Transfer Protocol - HTTP File Transfer Protocol - FTP Trivial File Transfer Protocol - TFTP Bootstrap Protocol - BOOTP Post Office Protocol - POP Internet Message Access Protocol - IMAP
List the protocols that fall under the TCP/IP model Application layer.
A home router.
On a home network, which device is most likely to provide dynamic IP addressing to clients on the home network?
SMB
The _______________ is a client-server file-sharing protocol, developed by IBM in the late 1980s, to describe the structure of shared network resources, such as directories, files, printers, and serial ports. It is a request-response protocol.
If Cisco decides to change the numeric address of www.cisco.com, it is transparent to the user because the domain name remains the same. The new address is simply linked to the existing domain name and connectivity is maintained.
On the Internet, domain names, such as http://www.cisco.com, are much easier for people to remember than 198.133.219.25, which is the numeric address for this server. Explain what happens if Cisco decides to change the numeric address of www.cisco.com.
user
The application layer is closest to _____________
Microsoft
SMB file-sharing and print services have become the mainstay of _________________ networking.
Start, authenticate, and terminate sessions. Control file and printer access. Allow an application to send or receive messages to or from another device.
SMB messages can:
DHCPREPORT
Select the item that is not a DHCPv4 process.
Hypertext Transfer Protocol - TCP 80, 8080
Set of rules for exchanging text, graphic images, sound, video, and other multimedia files on the World Wide Web.
File Transfer Protocol - TCP 20 to 21
Sets rules that enable a user on one host to access and transfer files to and from another host over a network. A reliable, connection-oriented, and acknowledged file delivery protocol.
P2P networks and P2P applications.
The P2P network model involves two parts, these are
application, presentation, and session
The TCP/IP application layer effectively consists of which three OSI layers?
Application, presentation, and session
The TCP/IP model Application layer is equal to which three OSI model layers?
DNS resolver
The DNS client, is sometimes called the _____________________________.
True
The presentation layer formats data for the application layer and it sets standards for file formats.
False
The presentation layer handles the exchange of information to initiate dialogs, to keep them active, and to restart sessions that are disrupted or idle for a long period of time.
Formatting, or presenting, data at the source device into a compatible form for receipt by the destination device. Compressing data in a way that can be decompressed by the destination device. Encrypting data for transmission and decrypting data upon receipt.
The presentation layer has three primary functions. These are:
DNS
The purpose of ___________ is to provide domain name to address resolution allowing users to access with names rather than their ip addresses.
Hypertext Transfer Protocol - HTTP Simple Mail Transfer Protocol - SMTP Post Office Protocol - POP
Three application layer protocols that are involved in everyday work or play are:
False
We use pop/imap to send email and smtp to receive.
Application
What TCP/IP layer supports the exchange of data between programs running on the source and destination hosts?
Application layer protocols are used.
What TCP/IP layer supports the exchange of data between programs running on the source and destination hosts?
Gnutella
What is a common protocol that is used with peer-to-peer applications such as WireShare, Bearshare, and Shareaza?
SMB clients can establish a long-term connection to the server.
What is an advantage of SMB over FTP?
The application layer is responsible for directly accessing the underlying processes that manage and deliver communication to the human network. This layer serves as the source and destination of communications across data networks. The application layer applications, services, and protocols enable users to interact with the data network in a way that is meaningful and effective.
What is the application layer responsible for?
On both the client and the server.
Where must SMTP be running in order to operate correctly?
ipconfig /displaydns
Which Microsoft DOS command displays all of the cached DNS entries on a Windows computer system?
Application
Which TCP/IP model layer is closest to the end user?
nslookup
Which command is used to manually query a DNS server to resolve a specific host name?
POP3
Which protocol can be used to transfer messages from an email server to an email client?
DHCP
Which protocol is not normally used by email users and servers used to process email?
session layer application layer presentation layer
Which three layers of the OSI model provide similar network services to those provided by the application layer of the TCP/IP model?
HTTP MPEG GIF
Which three protocols or standards are used at the application layer of the TCP/IP model?
It is a more efficient way to manage IP addresses than static address assignment.
Why is DHCP preferred for use on large networks?
P2P networks do not use centralized user accounts or access servers to maintain permissions. User accounts and access rights must be set individually on each peer device.
Why is it difficult to enforce security and access policies in P2P networks containing more than just a few computers?
