Quick Answer: Is SMTP A TCP Or UDP?

SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel.

In addition, the Internet Assigned Numbers Authority has allocated port 25 for both TCP and UDP for use by SMTP.

SMTP is a mail transport protocol, and in mail every single packet is important.

What protocol does SMTP use?

Simple Mail Transfer Protocol


Protocol dependencies

Typically, SNMP uses UDP as its transport protocol. The well known UDP ports for SNMP traffic are 161 (SNMP) and 162 (SNMPTRAP). It can also run over TCP, Ethernet, IPX, and other protocols. ATM uses SNMP as its ILMI (Integrated Local Management Interface) protocol.

Which protocol and port number is associated with SMTP?

SMTP servers commonly use the Transmission Control Protocol on port number 25.

Is port 587 TCP or UDP?

Port 587 Details


Does FTP use TCP or UDP?

FTP itself uses the TCP transport protocol exclusively, or in other words, it never uses UDP for its transport needs. Typically an application layer protocol will use one or the other. One notable exception to that is DNS or Domain Name System. FTP also is odd in the fact that it uses two ports to accomplish its task.

Is DNS a TCP or UDP?

UDP packets can not be greater then 512 bytes. DNS uses TCP for Zone transfer and UDP for name queries either regular (primary) or reverse. UDP can be used to exchange small information whereas TCP must be used to exchange information larger than 512 bytes.

Is port 161 UDP or TCP?

SNMP-TRAP allows the agent to send information about itself to the manager on port UDP/162. TCP can be used for both 161/162, but UDP tends to be more common. Typically the agents are configured in read-only or read-write mode. There are several versions of SNMP V1, V2c and V3.

Does SMB use UDP?

The purpose of UDP traffic in SMB/CIFS is to enable fast broadcast lookups on a local network. UDP traffic is used to look up workstation and server names, maintain browse lists, and other broadcast and directed lookups of workstation, server and domain names. The NetBIOS Name service operates on UDP port 137.

What port is SNMP on?

SNMP operates in the application layer of the Internet protocol suite. All SNMP messages are transported via User Datagram Protocol (UDP). The SNMP agent receives requests on UDP port 161. The manager may send requests from any available source port to port 161 in the agent.

What is the SMTP port number?




What are the most common SMTP ports?

Today, the most common SMTP ports are 25, 465, 587, or 2525.

How do I find my SMTP server name and port?

If you are using windows do the following:

  • Open up a command prompt (CMD.exe)
  • Type nslookup and hit enter.
  • Type set type=MX and hit enter.
  • Type the domain name and hit enter, for example: google.com.
  • The results will be a list of host names that are set up for SMTP.