Network Fundamentals Chapter 3

Port number 80 is the standard port used for HTTP (Hypertext Transfer Protocol) communication. When a client sends an HTTP request to a server, it uses port 80 by default. Similarly, when a server responds to the client's request, it sends the response back using port 80. This port number is well-known and widely used for web browsing and other HTTP-based applications.

HTTPS (Hypertext Transfer Protocol Secure) is a secure version of HTTP that is used to transmit sensitive information securely over the internet. The port number 443 is specifically assigned for HTTPS communication. When a user accesses a website using HTTPS, the data is encrypted and transmitted over port 443, ensuring that the information remains confidential and protected from unauthorized access.

The port number for telnet is 23. Telnet is a protocol that allows users to remotely access and manage devices or systems over a network. The port number serves as a virtual address that helps to establish a connection between the client and the server. In the case of telnet, port 23 is used as the default port for communication.

The port number for simple mail transfer protocol (SMTP) is 25.

FTP (File Transfer Protocol) uses two ports: port 20 for data transfer and port 21 for control commands. Port 20 is used for the actual transfer of data between the FTP server and client, while port 21 is used for establishing the initial connection and sending control commands. These two ports work together to facilitate the efficient transfer of files over a network using FTP.

The port number for the domain name system (DNS) is 53. DNS is responsible for translating domain names into IP addresses, allowing users to access websites using easy-to-remember domain names instead of complex numerical IP addresses. Port numbers are used to identify specific processes or services running on a device, and port 53 is specifically reserved for DNS. It allows DNS messages to be sent and received between DNS servers and clients, facilitating the translation of domain names to IP addresses and vice versa.

The port number for post office protocol (POP) is 110. This is the default port used by POP to receive incoming email messages from a mail server. POP is a protocol used by email clients to retrieve email messages from a mail server. By using port number 110, the email client can establish a connection with the mail server and download the emails stored on the server.

The port number for DHCP is 67. This port number is used by DHCP servers to listen for client requests and provide them with IP addresses and other network configuration information. DHCP (Dynamic Host Configuration Protocol) is a network protocol that allows devices to obtain IP addresses automatically, eliminating the need for manual configuration. By using port number 67, DHCP servers can efficiently communicate with clients and assign them unique IP addresses within a network.

The correct answer is GET, POST, and PUT because these are three common message types used in web development and API communication. GET is used to retrieve data from a server, POST is used to send data to a server to create a new resource, and PUT is used to update an existing resource on the server. The options "GOT" and "SHOT" are not valid message types in this context.

The DNS server stores different types of resource records to resolve names. The A record is used to map a domain name to an IP address. The NS record identifies the authoritative DNS servers for a domain. The MX record specifies the mail server responsible for accepting email messages for a domain. Therefore, A, NS, and MX are all valid types of resource records stored in a DNS server.