The protocol for sending and receiving emails on the Internet does not include "ARP". There are three protocols for sending and receiving emails: SMTP, POP3, and IMAP4. ARP is an address resolution protocol. It is a TCP/IP protocol that obtains physical addresses based on IP addresses. It can be used to query the correspondence between IP addresses and MAC addresses in the local ARP cache, add or delete static correspondence, etc.; ARP protocol Not used for sending and receiving emails.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
The protocol for sending and receiving E-Mail on the Internet does not include ____.
A. SMTP
B. POP3
C. ARP
D. IMAP
Answer: C. ARP
The protocols for sending and receiving E-Mail, that is, the email protocols include SMTP, POP3, and IMAP4. They all belong to the TCP/IP protocol cluster. By default, Connections are established via TCP ports 25, 110 and 143 respectively. The ARP protocol is not included, so select C.
SMTP Protocol
The full name of SMTP is "Simple Mail Transfer Protocol", which is the simple mail transfer protocol. It is a set of specifications for transmitting mail from a source address to a destination address, which controls how the mail is transferred. The SMTP protocol belongs to the TCP/IP protocol suite and helps each computer find the next destination when sending or relaying letters. The SMTP server is a sending email server that follows the SMTP protocol. SMTP authentication, simply put, requires that you must provide an account name and password before you can log in to the SMTP server, which leaves no opportunity for those who spread spam. The purpose of adding SMTP authentication is to protect users from spam.
SMTP has become the de facto standard for E-Mail transmission.
POP Protocol
POP Post Office Protocol is responsible for retrieving emails from the mail server. It requires the mail server to complete one of the following tasks: retrieve the mail from the mail server and delete the mail from the server; retrieve the mail from the mail server but not delete it; do not retrieve the mail and just ask if any new mail has arrived. The POP protocol supports the Multi-User Internet Mail Extension, which allows users to attach binary files to emails, such as word processing files and spreadsheet files. This allows virtually any file format to be transferred, including images and sound files. When the user reads the mail, the POP command downloads all the mail information to the user's computer immediately and does not keep it on the server.
POP3 (Post Office Protocol 3) is the third version of the Post Office Protocol and is the first offline protocol standard for Internet email.
IMAP Protocol
Internet Information Access Protocol (IMAP) is a new protocol that is superior to POP. Like POP, IMAP can download mail, delete mail from the server, or ask for new mail, but IMAP overcomes some of POP's shortcomings. For example, it can determine how the client requests the mail server to submit incoming mail, requesting the mail server to download only selected messages rather than all messages. The client can read the title of the email message and the name of the sender before deciding whether to download the email. Through the user's client email program, IMAP allows users to create and manage mail folders or mailboxes on the server, delete mail, and query part or all of a letter, all without removing the mail from the server. Downloaded to the user's personal computer.
Commonly used email clients that support IMAP include: ThunderMail, Foxmail, Microsoft Outlook, etc.
ARP Protocol
ARP (Address Resolution Protocol) is a TCP/IP protocol that obtains a physical address based on an IP address. When the host sends information, it broadcasts the ARP request containing the target IP address to all hosts on the local area network, and receives the return message to determine the physical address of the target; after receiving the return message, the IP address and physical address are stored in the local machine. The ARP cache is kept for a certain period of time, and the ARP cache is directly queried on the next request to save resources. The address resolution protocol is based on mutual trust between hosts in the network. Hosts on the local area network can send ARP response messages independently. When other hosts receive the response message, they will not detect the authenticity of the message and will discard it. Recorded in the local ARP cache; thus the attacker can send a fake ARP reply message to a certain host, so that the information sent cannot reach the expected host or reaches the wrong host, which constitutes an ARP spoofing. The ARP command can be used to query the correspondence between IP addresses and MAC addresses in the local ARP cache, add or delete static correspondence, etc. Relevant protocols include RARP and proxy ARP. NDP is used to replace Address Resolution Protocol in IPv6.
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