uCertify Chapter 6
You need to have secure communications using HTTPS. What port number is used by default?
443; HTTPS, or Secure HTTP, uses port 443 by default.
If a client can ping a website by IP address but not by hostname, or FQDN, which of the following (80/ 69/ 53/ 23/ 21) port numbers should be checked for resolving the problem?
53; The problem is with DNS, which uses both TCP and UDP port 53.
File Transfer Protocol (FTP)
A TCP/IP protocol and software that permit the transferring of files between computer systems. Because FTP has been implemented on numerous types of computer systems, files can be transferred between disparate computer systems (for example, a personal computer and a minicomputer).
Hypertext Transfer Protocol over SSL (HTTPS)
A Uniform Resource Identifier (URI) scheme used to indicate a secure communication such as payment transactions and corporate information systems.
Multicast group
A defined set of users or hosts that are allowed to read or view data sent via multicast. Multicast works by sending messages or data to IP multicast group addresses.
DoD Networking Model
A four-layer conceptual model describing how communications should take place between computer systems. The four layers are Process/Application, Host-to-Host, Internet, and Network Access.
Host-to-Host layer
A layer in the DoD model that corresponds to the Transport layer of the OSI model.
Datagram
A logical collection of information transmitted as a Network layer unit over a medium without a previously established virtual circuit. IP datagrams have become the primary information unit of the Internet. At various layers of the OSI reference model, the terms cell, frame, message, packet, and segment also define these logical information groupings.
Internet Control Message Protocol (ICMP)
A message and management protocol for TCP/IP. The ping utility uses ICMP.
Remote Desktop Protocol (RDP)
A multichannel protocol that allows a user to connect to a computer running Microsoft Remote Desktop Services. The server listens by default on TCP port 3389.
Secure Shell (SSH)
A network protocol that allows data to be exchanged using a secure channel between two networked devices.
SSH File Transfer Protocol (SFTP)
A network protocol that provides file transfer over any reliable data stream. It is typically used with SSHv2 (TCP port 22) to provide secure file transfer but is intended to be usable with other protocols as well.
Simple Mail Transfer Protocol (SMTP)
A program that looks for mail on SMTP servers and sends it along the network to its destination at another SMTP server.
User Datagram Protocol (UDP)
A protocol at the Host-to-Host layer of the DoD model that corresponds to the Transport layer of the OSI model. Data segments are divided, sent randomly, and put back together at the receiving end. This is a connectionless protocol.
Trivial File Transfer Protocol (TFTP)
A protocol similar to FTP that does not provide the security or error-checking features of FTP.
Three-way handshake
A term used in a TCP session to define how a virtual circuit is set up. It is called this because it uses three data segments.
Connection-oriented transport protocol
A transport protocol that establishes a virtual connection between sending and receiving stations before any user data is transmitted between them. TCP is a connection-oriented protocol.
Connectionless transport protocol
A transport protocol, such as UDP, that does not create a virtual connection between sending and receiving stations before transmitting user data between them.
Connection-oriented
A type of communication between two hosts that establishes a session for synchronizing sent data. If the service is also reliable, the data is acknowledged by the receiving device. This allows for guaranteed delivery of data between PCs.
Connectionless
A type of communication between two hosts where no session is established for synchronizing sent data. If the service is also unreliable, the data is not acknowledged at the receiving end. This can allow for data loss.
What protocol is used to find the hardware address of a local device?
ARP; Address Resolution Protocol (ARP) is used to find the hardware address of a local device from a known IP address.
The OSI model has seven layers and the DoD has four. At which layer does SMTP works in both models?
Application; SMTP resides at the Application layer of the OSI and DoD models.
Fully Qualified Domain Name (FQDN)
An address that uses both the hostname (workstation name) and the domain name.
Electronic mail (email) software
An application that allows people to send messages via their computers on the same network or over the Internet.
Cyclic Redundancy Check (CRC)
An error-checking method in data communications that runs a formula against data before transmissions. The sending station then appends the resultant value (called a checksum) to the data and sends it. The receiving station uses the same formula on the data. If the receiving station doesn't get the same checksum result for the calculation, it considers the transmission invalid, rejects the frame, and asks for retransmission.
Which of the following services use UDP? (DHCP/ SMTP/ SNMP/ FTP/ HTTP/ TFTP) Each correct answer represents a complete solution. Choose three.
DHCP, SNMP, and TFTP use UDP; whereas SMTP, FTP, and HTTP use TCP
You want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this?
DHCP; Dynamic Host Configuration Protocol (DHCP) is used to provide IP information to hosts on your network. DHCP can provide a lot of information, but the most common is IP address, subnet mask, default gateway, and DNS information.
Which of the following (SMTP/ Telnet/ DNS/ FTP) uses both TCP and UDP?
DNS; DNS uses TCP for zone exchanges between servers and uses UDP when a client is trying to resolve a hostname to an IP address.
You need to transfer files between two hosts. Which protocol can you use?
FTP; File Transfer Protocol (FTP) can be used to transfer files between two systems.
What layer in the IP stack is equivalent to the Transport layer of the OSI model?
Host-to-Host; The four layers of the IP stack (also called the DoD model) are Application/Process, Host-to-Host, Internet, and Network Access. The Host-to-Host layer is equivalent to the Transport layer of the OSI model.
Which of the following describe the DHCP Discover message? Each correct answer represents a complete solution. Choose two.
It uses UDP as the Transport layer protocol & It uses FF:FF:FF:FF:FF:FF as a Layer 2 broadcast. A client that sends out a DHCP Discover message in order to receive an IP address sends out a broadcast at both Layer 2 and Layer 3. The Layer 2 broadcast is all Fs in hex, or FF:FF:FF:FF:FF:FF. The Layer 3 broadcast is 255.255.255.255, which means all networks and all hosts. DHCP is connectionless, which means it uses User Datagram Protocol (UDP) at the Transport layer, also called the Host-to-Host layer.
Internet layer
Layer in the Internet Protocol suite of protocols that provides network addressing and routing through an internetwork.
You need to make sure that the time is consistent across all your network devices. What protocol do you need to run on your network?
NTP; Network Time Protocol will ensure a consistent time across network devices on a network.
You need to have a connection to remotely run applications that are installed only on your desktop computer at your office. Which protocol will provide a GUI interface to your work computer?
RDP; Remote Desktop Protocol (RDP) allows you to connect to a remote computer and run programs, as Telnet does. However, a bigger advantage that RDP has over Telnet is that RDP allows you to have a GUI interface connection.
Which of the following services use TCP? (DHCP/ SMTP/ NTP/ FTP/ HTTP/ TFTP) Each correct answer represents a complete solution. Choose all that apply.
SMTP, FTP, HTTP; SMTP, FTP, and HTTP are connection-oriented protocols and therefore, use TCP.
Which of the following (IMAP/ POP3/ HTTP/ SMTP) protocols is used by clients to send emails?
SMTP; SMTP is used by clients for sending emails to an email server. POP3 and IMAP are used by clients to retrieve their emails from the server that stores it until it is retrieved. HTTP is only used with web-based mail services.
Which of the following (DNS, SNMP, SMTP, TCP) protocols can use TCP and UDP, permit authentication and secures polling of network devices, and allow for automated alerts and reports on network devices?
SNMP; Simple Network Management Protocol is typically implemented using version 3, which allows for a connection-oriented service, authentication and secure polling of network devices, and alerts and reports on network devices.
You need to log in to a Unix server across a network that is not secure. Which of the following (HTTP/ SFTP/ SSH/ Telnet) protocols will allow you to remotely administer this server securely?
SSH; Secure Shell (SSH) allows you to remotely administer routers, switches, and even servers securely.
What Layer 4 protocol with its default port should be used for a Telnet connection?
TCP, 23; Telnet uses TCP at the Transport layer with a default port number of 23.
Which of the following TCP/IP protocols (TCP/ Telnet/ FTP/ TFTP/ IP) are used at the Application layer of the OSI model? Each correct answer represents a complete solution. Choose three.
Telnet, FTP, TFTP; Telnet, File Transfer Protocol (FTP), and Trivial FTP (TFTP) are all Application layer protocols. IP is a Network layer protocol. Transmission Control Protocol (TCP) is a Transport layer protocol.
Network Access layer
The bottom layer in the Internet Protocol suite that provides media access to packets.
Address resolution
The process used for resolving differences between computer addressing schemes. Address resolution typically defines a method for tracing Network layer (Layer 3) addresses to Data Link layer (Layer 2) addresses.
Transmission Control Protocol (TCP)
The protocol found at the Host-to-Host layer of the DoD model. This protocol breaks data packets into segments, numbers them, and sends them in random order. The receiving computer reassembles the data so that the information is readable for the user. In the process, the sender and the receiver confirm that all data has been received; if not, it is resent. This is a connection-oriented protocol.
Internet Protocol (IP)
The protocol in the TCP/IP protocol suite responsible for network addressing and routing.
Transmission Control Protocol/Internet Protocol (TCP/IP)
The protocol suite developed by the DoD as an internetworking protocol suite that could route information around network failures. Today it is the de facto standard for communications on the Internet.
Hypertext Transfer Protocol (HTTP)
The protocol used for communication between a web server and a web browser.
Post Office Protocol version 3 (POP3)
The protocol used to download email from an SMTP email server to a network client.
Default gateway
The router that all packets are sent to when the workstation doesn't know where the destination station is or when it can't find the destination station on the local segment.
Which statements are true regarding ICMP packets? Each correct answer represents a complete solution. Choose two.
They are encapsulated within IP datagrams & they can provide hosts with info about network problems; Internet Control Message Protocol (ICMP) is used to send error messages through the network, but ICMP does not work alone. Every segment or ICMP payload must be encapsulated within an IP datagram (or packet).
Which of the following allows a server to distinguish among different simultaneous requests from the same host?
They use different port numbers. Through the use of port numbers, TCP and UDP can establish multiple sessions between the same two hosts without creating any confusion. The sessions can be between the same or different applications, such as multiple web-browsing sessions or a web-browsing session and an FTP session.
Port numbers
Used at the transport layer with TCP and UDP to keep track of host-to-host virtual circuits.