Beward N120 Installation & User Manual page 87

Shutter is the device on the camera that opens and closes to control how long the focal
plane is exposed to light.
SMTP is used for sending and receiving e-mail. However, as it is "simple," it is limited in its
ability to queue messages at the receiving end, and is usually used with one of two other protocols,
POP3 or IMAP. These other protocols allow the user to save messages in a server mailbox and
download them periodically from the server.
SMTP authentication is an extension of SMTP, whereby the client is required to log into the
mail server before or during the sending of email. It can be used to allow legitimate users to send
email while denying the service to unauthorized users, such as spammers.
SSL/TLS (Secure Socket Layer/Transport Layer Security). These two protocols (SSL is
succeeded by TLS) are cryptographic protocols that provide secure communication on a network.
SSL is commonly used over HTTP to form HTTPS, as used e.g. on the Internet for electronic
financial transactions. SSL uses public key certificates to verify the identity of the server.
Subnet & subnet mask is an identifiably separate part of an organization's network.
Typically, a subnet may represent all the machines at one geographic location, in one building, or
on the same local area network (LAN). Having an organization's network divided into subnets
allows it to be connected to the Internet with a single shared network address.
The subnet mask is the part of the IP address that tells a network router how to find the subnet that
the data packet should be delivered to. Using a subnet mask saves the router having to handle the
entire 32-bit IP address; it simply looks at the bits selected by the mask.
Switch is a network device that connects network segments together, and which selects a
path for sending a unit of data to its next destination. In general, a switch is a simpler and faster
mechanism than a router, which requires knowledge about the network and how to determine the
route. Some switches include the router function.
TCP is used along with the Internet Protocol (IP) to transmit data as packets between
computers over the network. While IP takes care of the actual packet delivery, TCP keeps track of
the individual packets that the communication (e.g. requested a web page file) is divided into, and,
when all packets have arrived at their destination, it reassembles them to re-form the complete file.
TCP is a connection-oriented protocol, which means that a connection is established
between the two end-points and is maintained until the data has been successfully exchanged
between the communicating applications.
Time to live (TTL) is mechanism that limits the lifespan of data in a computer or network.
TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once
the prescribed event count or timespan has elapsed, data is discarded. In computer networking,
TTL prevents a data packet from circulating indefinitely. In computing applications, TTL is used to
improve performance of caching or improve privacy.
N120 Installation User Manual
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