Objective 1.1

You need to log in to a Unix server across a network that is not secure. Which of the following 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.)

Which of the following is a security protocol that combines digital certificates for authentication with public key data encryption?

SSL (Secure Sockets Layer (SSL) is a security protocol that combines digital certificates for authentication with public key data encryption. SSL is a server-driven process; any web client that supports SSL, including all current web browsers, can connect securely to an SSL-enabled server. It is a cryptographic protocol that provides communication security over a computer network.)

Host 1 sent a SYN packet to Host 2. What will Host 2 send in response?

SYN/ACK (A connection-oriented session is set up using what is called a three-way handshake. The transmitting host sends a SYN packet, the receiving host sends a SYN/ACK, and the transmitting host replies with the last ACK packet. The session is now set up.)

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 Application layer protocols is not connection-oriented?

TFTP (Trivial File Transfer Protocol (TFTP) works at the Application layer and uses UDP port 69. It is considered unreliable and not connection-oriented.)

How does a server can distinguish among different simultaneous services from the same host?

The requests have 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.)

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.)

A company wants to make the corporate emails secure from network attacks such as phishing. The network technician has decided to install a port security firewall for this purpose. On which of the following ports should this be enabled to have the desired result?

-143 -110 -25 (The port security feature should be enabled on port numbers 25, 110, and 143. These are the port numbers used by email protocols. Port 25 used by SMTP for sending emails. Ports 110 and 143 are used by POP3 and IMAP4 for retrieving emails from an email server.)

Which of the following ports is used when accessing a website with SSL encryption?

443 (Secure Sockets Layer (SSL) is a security protocol that combines digital certificates for authentication with public key data encryption. SSL is a server-driven process; any web client that supports SSL, including all current web browsers, can connect securely to an SSL-enabled server. It is used specifically to protect network traffic. It uses port 443 as the default port.)

A network technician in a company receives complaints from users that they are unable to access certain VoIP applications. Which of the following ports should the network technician check to solve this issue?

5060 (The network administrator should check port 5060. TCP port 5061 and UDP port 5060 is used by SIP which is a signaling, setup, and management protocol used with voice and video sessions over IP (VoIP) networks. SIP, in conjunction with other protocols, also specifies the encoder/decoder (codec) that would be used for voice and video connections over the network.)

Which of the following ports needs to be opened on the firewall for DNS?

53 (DNS uses the TCP/UDP port number 53 to resolve domain names to corresponding IP addresses.)

If a client can ping a website by IP address but not by hostname, or FQDN, which of the following port numbers should be checked for resolving the problem?

53 (The problem is with DNS, which uses both TCP and UDP port 53.)

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.)

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 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.)

A receiving host has failed to receive all the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

Decrease the window size. (A receiving host can control the transmitter by using flow control (TCP uses windowing by default). By decreasing the window size, the receiving host can slow down the transmitting host so the receiving host does not overflow its buffers.)

Which of the following is considered reliable?

FTP (FTP uses TCP at the Transport layer. Transmission Control Protocol (TCP) is a Transport layer protocol that offers full-duplex, connection-oriented, and reliable communication.)

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.)

Ann, on her regular business trip connects to a hotel's wireless network to send emails to customers. Next day she notices that emails have been sent from her account without her consent. Which protocol is used to compromise her email password utilizing a network sniffer?

HTTP (The HTTP protocol sends data in plain text. Therefore, a network sniffer or a packet sniffer can be used to capture an HTTP packet by an attacker. The data then can be read by an attacker, perhaps allowing the attacker to see confidential information.)

What protocol from the Internet Protocol (IP) stack is used for diagnostics and error messages?

ICMP (Internet Control Message Protocol (ICMP) works at the Network layer and is used by IP for many different services. It is a management protocol and messaging service provider for IP. It is used for diagnostics (ping and traceroute) and for sending error messages through the network.)

A network administrator wants a central time source for the entire company's network so that all network devices will synchronize properly. Which network protocol could be used for this purpose?

NTP (Network Time Protocol (NTP) will ensure that the time is consistent across all network devices on the domain. It synchronizes the time of a computer client or server to another server or reference time source, such as a radio or satellite receiver or modem. It uses port 123 for communication and works at the Transport layer of the OSI.)

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.)

Which of the following VPN protocols runs over port 1723 and allows encryption to be done at the data level?

PPTP (PPTP is a VPN protocol that was created by Microsoft and uses port 1723 to encrypt data at the data level.)

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 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.)

Your company has two mail servers responsible for sending, receiving, and managing emails. Which of the following network protocols will you use to transfer emails between servers?

SMTP (You will use the Simple Mail Transfer Protocol (SMTP) to transfer emails between mail servers. In addition, SMTP is generally used to send emails from a mail client to a mail server. SMTP typically uses TCP port 25.)

You need a protocol that will help you simplify the process of setting up a network and administering it. Which of the following will you use?

SNMP (SNMP can be used to manage the network, but it also helps in simplifying the process of setting up a network and administering it. SNMP uses UDP port 161 to monitor and manage network devices, such as routers, switches, and servers.)

Which of the following 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.)

What is the default port number for SSH?

22 (SSH uses port 22 by default. Secure Shell is a network protocol that is designed as an alternative to command-based utilities such as Telnet that transmit data in clear text. It creates a secure channel between the devices and provides confidentiality and integrity of the data transmission.)

What is the well-known port number for Telnet?

23 (The Telnet protocol uses TCP port 23 to connect to a remote host (typically via a terminal emulator).)

What is the well-known port number for SMTP?

25 (The well-known port number for SMTP is 25. SMTP is used by a client to send email to a server or by a server to send emails to another server.)

A network administrator creates a virtual machine in the cloud. The employees also want to connect to it remotely using RDP. Which of the following default ports needs to be opened for this purpose?

3389 (TCP port 3389 is used by Remote Desktop Protocol (RDP), which is a Microsoft protocol that allows a user to view and control the desktop of a remote computer. RDP is an excellent tool for remote clients, allowing them to connect to their work computer from home or perform work on other applications without running or installing any of the software on their home computer. RDP works somewhat like telnet. However, the large advantage that RDP has over Telnet is that RDP provides a GUI interface connection.)

What is the default port number for HTTPS?

443 (HTTPS uses TCP port 443 to securely retrieve content from a web server.)

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.)

A company switches to a VoIP PBX network from the traditional PBX system. The network utilizes the SIP protocol for all the communications. However, the network technician has been receiving complaints from the users that they are unable to call. Upon troubleshooting, the network administrator finds that the firewall is blocking the required ports. Which of the following ports should be opened on the firewall for proper communication?

-5060 -5061 (SIP uses TCP port 5061 and UDP port 5060 for creating and terminating sessions for one or more media connections, including Voice over IP calls. SIP is a signaling protocol that sets up and manage voice and video sessions over IP networks such as VoIP telephones.) (A SIP Trunk is a Voice over Internet Protocol (VoIP) technology based on the Session Initiation Protocol (SIP). It is a link that provides streaming media and unified communications to an organization by an Internet telephony service provider. It connects to organizations equipped with SIP-based Private Branch Exchange (PBX) systems and Unified Communications (UC) facilities.)

A network technician is setting up a web server for hosting a web application of a company. Both secured and unsecured access have to be provided to the front end. Which of the following ports must be opened for this?

-80 -443 (HTTP and HTTPS are the protocols that are used to manage communications between web browsers and web servers and they open the right resource when a link is clicked. HTTP uses TCP port 80 while HTTP uses TCP port 443 to retrieve content from a web server. HTTPS is a secure version of HTTP that provides many security tools for keeping communications between a web browser and a server secure.)

James, a server administrator, is setting up a new server for the company's network. Which port and service should he open to allow the newly installed server to assign IP addresses for the devices connecting with the network?

-DHCP -67 (James should open the DHCP service on the server that uses UDP ports 67 and 68 for dynamically assigning IP addresses to clients on the network. UDP port number 67 is the destination port of a server, and UDP port number 68 is used by the client. DHCP lets a network or server administrator supervise and distribute IP addresses from a central point and automatically sends a new IP address when a computer is plugged into a different place in the network.)

You need to transfer files between two systems. Which of the following protocols can be used?

-FTP -SCP (File Transfer Protocol (FTP) and Secure Copy Protocol (SCP) can be used to transfer files on a network. FTP protocol transfers files across an IP network, and it can accomplish this between any two machines that are using it. The problem with FTP is that all data is sent in clear text. SCP provides a secure file-transfer service over an SSH connection and offers a file's original date and time information, which is not available with FTP.)

Which of the following services use TCP?

-FTP -SMTP -HTTP (SMTP, FTP, and HTTP are connection-oriented protocols and therefore, use TCP.)

A company has decided to switch to a VoIP PBX network from the traditional PBX system. Which of the following protocols will be in use over the newly formed VoIP network?

-SIP -RTP -H.323 (A Voice over IP (VoIP) network digitizes the spoken voice into packets and transmits those packets across a data network. This allows voice, data, and even video to share the same medium. Some of the common protocols used over a VoIP network are: Session Initiation Protocol (SIP): It is a signaling, setup, and management protocol used with voice and video sessions over IP networks. SIP, in conjunction with other protocols, also specifies the encoder/decoder (codec) that will be used for voice and video connections over the network. Real-time Transport Protocol (RTP): It is a protocol that carries voice and interactive video over a VoIP network. H.323: It is a signaling protocol that provides multimedia communications over a network. It is an example of a session layer protocol, which can help set up, support, and tear down a voice or video connection.)

Which of the following services use UDP?

-SNMP -DHCP -TFTP (DHCP, SNMP, and TFTP use UDP. Whereas, SMTP, FTP, and HTTP use TCP.)

A network technician has been asked to configure an email server that will use secure protocols. On completing the upgrade, which of the following ports on the firewall should be configured to allow for connectivity?

-TCP 587 -TCP 993 -TCP 995 (SMTP, POP3, and IMAP are the three important email protocols. By default, these protocols use TCP ports 25, 110, and 143, respectively. SMTP is used for sending emails while POP3 and IMAP are used for receiving emails. However, the default ports are not secure and since the network technician has to configure the email server using secure protocols, the ports that should be configured on the firewall are TCP ports 587, 993, and 995. TCP port 587 is the secure port (secure over TLS) used by SMTP, TCP port 993 is the secure port (secure over SSL) used by IMAP, and TCP port 995 is the secure port (secure over SSL) used by POP3, respectively.)

Which of the following TCP/IP protocols are used at the Application layer of the OSI model?

-Telnet -TFTP -FTP (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.)

Which statements are true regarding ICMP packets?

-They are encapsulated within IP datagrams. -They can provide hosts with information 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 UDP ports is used by NTP?

123 (Network Time Protocol (NTP) is used by a network device to synchronize its clock with a time server (NTP server).)