Service status report

Server_name(xxx.xxx.xxx.xxx) is the server name and it also shows the IP address of the server.

FTP (File Transfer Protocol) FTP runs over the Transmission Control Protocol (TCP).[1] Usually FTP servers listen on the well-known port number 21 (IANA-reserved) for incoming connections from clients. A connection to this port from the FTP client forms the control stream on which commands are passed to the FTP server and responses are collected. FTP uses out-of-band control; it opens dedicated data connections on other port numbers. The parameters for the data streams depend on the specifically requested transport mode. Data connections usually use port number 20.
In active mode, the FTP client opens a dynamic port, sends the FTP server the dynamic port number on which it is listening over the control stream and waits for a connection from the FTP server. When the FTP server initiates the data connection to the FTP client it binds the source port to port 20 on the FTP server.
In order to use active mode, the client sends a PORT command, with the IP and port as argument. The format for the IP and port is “h1,h2,h3,h4,p1,p2″. Each field is a decimal representation of 8 bits of the host IP, followed by the chosen data port. For example, a client with an IP of 192.168.0.1, listening on port 49154 for the data connection will send the command “PORT 192,168,0,1,192,2″. The port fields should be interpreted as p1×256 p2 = port, or, in this example, 192×256 2 = 49154.
In passive mode, the FTP server opens a dynamic port, sends the FTP client the server’s IP address to connect to and the port on which it is listening (a 16-bit value broken into a high and low byte, as explained above) over the control stream and waits for a connection from the FTP client. In this case, the FTP client binds the source port of the connection to a dynamic port. Read more (source: Wikipedia.org).

HTTP (Hypertext Transfer Protocol) is an application-level protocol for distributed, collaborative, hypermedia information systems. Its use for retrieving inter-linked resources, called hypertext documents, led to the establishment of the World Wide Web in 1990 by English physicist Tim Berners-Lee. There are two major versions, HTTP/1.0 that uses a separate connection for every document and HTTP/1.1 that can reuse the same connection to download, for instance, images for the just served page. Hence HTTP/1.1 may be faster as it takes time to set up the connections.
The standards development of HTTP has been coordinated by the World Wide Web Consortium and the Internet Engineering Task Force (IETF), culminating in the publication of a series of Requests for Comments (RFCs), most notably RFC 2616 (June 1999), which defines HTTP/1.1, the version of HTTP in common use.
HTTP is a request/response standard as is typical in client-server computing. A client is the application (web browser, spider) or computer used by an end-user, the server is the computer hosting a web site. The client submitting HTTP requests is referred to as the user agent. The responding server—which stores or creates resources such as HTML files and images—is called the origin server. In between the user agent and origin server may be several intermediaries, such as proxies, gateways, and tunnels. HTTP is not constrained in principle to using TCP/IP, although this is its most popular application via the Internet. Indeed HTTP can be “implemented on top of any other protocol on the Internet, or on other networks.” HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used.” Read more (source: Wikipedia.org).

IMAP (Internet Message Access Protocol) and previously called Internet Mail Access Protocol, Interactive Mail Access Protocol (RFC 1064), and Interim Mail Access Protocol) is an Application Layer Internet protocol operating on port 143 that allows an e-mail client to access e-mail on a remote mail server. The current version, IMAP version 4 revision 1 (IMAP4rev1), is defined by RFC 3501.
IMAP supports both on-line and off-line modes of operation. E-mail clients using IMAP generally leave messages on the server until the user explicitly deletes them. This and other facets of IMAP operation allow multiple clients to access the same mailbox. Most e-mail clients support either POP or IMAP to retrieve messages; however, fewer Internet Service Providers (ISPs) support IMAP. IMAP offers access to the mail store; the client may store local copies of the messages, but these are considered to be a temporary cache; the server’s store is authoritative.
E-mail messages are usually sent to an e-mail server that stores received messages in the recipient’s e-mail mailbox. The user retrieves messages with either a web browser or an e-mail client that uses one of a number of e-mail retrieval protocols.
E-mail clients can usually be configured to use either POP or IMAP to retrieve e-mail and in both cases use SMTP for sending. Most e-mail programs can also use Lightweight Directory Access Protocol (LDAP) for directory services.
IMAP is often used in large networks, for example, a college campus mail system. IMAP allows users to access new messages as fast as the network can deliver them to their computers. With POP, users either download the e-mail to their computer or access it via the web. Both methods take longer than IMAP over a local network, and the user must download any new mail (e.g. by “refreshing” the page) to see the new messages. Read more (source: Wikipedia.org).

POP3 (Post Office Protocol) The Post Office Protocol has undergone several revisions. It is customary to append the version number to the protocol’s acronym. POP3 has made earlier versions of the protocol, informally called POP1 and POP2, obsolete. In contemporary usage, the term POP is almost always associated with the latest version.
The design of POP and its procedures supports end-users with temporary Internet connections, such as dial-up access, allowing these users to retrieve e-mail when connected and then to view and manipulate the retrieved messages when offline. Although most clients have an option to leave mail on server, e-mail clients using POP generally connect, retrieve all messages, store them on the user’s PC as new messages, delete them from the server, and then disconnect.
Clients with a leave mail on server option generally use the POP3 UIDL (Unique IDentification Listing) command. Most POP3 commands identify specific messages by their ordinal number on the mail server. This creates a problem for a client intending to leave messages on the server, since these message numbers may change from one connection to the server to another. For example if a mailbox contained five messages, and a different client then deletes message #3, the next connecting user will find the last two messages’ numbers decremented by one. UIDL provides a mechanism to avoid these numbering issues by assigning a string of characters as a permanent and unique ID for the message. Read more (source: Wikipedia.org).

SMTP (Simple Mail Transfer Protocol) is a relatively simple, text-based protocol, in which a mail sender communicates with a mail receiver by issuing simple command strings and supplying necessary data over a reliable ordered data stream channel, typically a Transmission Control Protocol (TCP) connection. An SMTP session consists of a series of commands, initiated by the SMTP client, and responses from the SMTP server through which the session is opened, operating parameters are exchanged, the recipients are specified, and possibly verified, and the message is transmitted, before the session is closed. The originating host is either an end-user’s email client also known as mail user agent (MUA), or a relay server’s mail transfer agent (MTA).
SMTP was designed as an electronic mail transport and delivery protocol, and as such it is used between SMTP systems that are operational at all times. However, it has capabilities for use as a mail submission protocol for email clients (split user-agent) that do not have the capability to operate as MTA. Such agents are also called message submission agents (MSA),[13] sometimes also referred to as mail submission agents. They are typically end-user applications and send all messages through a smart relay server, often called the outgoing mail server, which is specified in the programs’ configuration. A mail transfer agent incorporated either in the e-mail client directly or in the relay server, typically determines the destination SMTP server by querying the Domain Name System for the mail exchanger (MX record) of each recipient’s domain name. Conformant MTAs fall back to a simple address lookup (A record) of the domain name when no mail exchanger is available. In some cases an SMTP client, even a server, may also be configured to use a smart host for delivery. The SMTP client typically initiates a Transmission Control Protocol (TCP) connection to the SMTP server on the well-known port designated for SMTP, port number 25. Read more (source: Wikipedia.org).

Server uptime is a measure of the time a computer system has been “up” and running. It came into use to describe the opposite of downtime, times when a system was not operational. The uptime and reliability of computer and communications facilities is sometimes measured in nines (similar to the unit of metallic purity). “Five nines” means 99.999% availability, which translates to a total downtime of approximately five minutes and fifteen seconds per year.
It is often used as a measure of computer operating system reliability and stability, in that this time represents the time a computer can be left unattended without crashing, or needing to be rebooted for administrative or maintenance purposes. Conversely, long uptime may indicate negligence, because critical updates can require reboots on some platforms. Read more (source: Wikipedia.org).