Glossary 9-19Appendix9SNTPSimple Network Time Protocol. A simplified version of NTP. This protocol enablescomputers in a network to synchronize their system times with a public time serverused around the world. The time public NTP servers provide is generally accurate towithin milliseconds.SpoolSimultaneous Peripheral Operations On-Line. “Spooling” means putting jobs in abuffer, which is a special area in memory or on a disk. Devices access data atdifferent rates. The buffer provides a holding area where the data is held until thedevice for which it is meant is ready to access it.SSLSecure Sockets Layer. A protocol that ensures security and privacy when transmittingprivate documents over the Internet.SSL encryptionSSL uses two keys to encrypt data: a public key, which is known to “everyone,” and aprivate or secret key, which is known only to the recipient of the message.Startup timeIf the machine is connected to a switching hub, it may not be able to connect to anetwork when it is powering ON. This occurs because the spanning tree process,performed between switching hubs, prevents them from communicating with eachother immediately after the machine connects to the network. A delay in the startuptime is necessary for the machine to connect to the network properly.SubnetA portion of a network, which may be a physically independent network segment, thatshares a network address with other portions of the network, and is distinguished bya subnet number. For example, all devices with IP addresses that start with100.100.100. would be part of the same subnet.Subnet MaskThe method used to determine to which subgroup, or subnet, an IP address belongs.On TCP/IP networks, all devices whose IP addresses have the same prefix wouldbelong to the same subnet. Dividing a network into subnets is useful for both securityand performance reasons.Switching hubA network connection box to which a number of computers can be connected.Conventional hubs send each data packet to every connected computer on thenetwork, whereas a switching hub forwards data packets from the network to theappropriate computer, according to the packet’s address. Since a switching hubforwards packets only to their intended recipients, it provides greater efficiency.
