ICND 1

Secure Hash Algorithm. SHA256 is part of the SHA2 set of cryptographic hash functions. 

SiteLevel Aggregator. 

stateless address autoconfiguration. Allows IPv6 hosts to automatically acquire a valid IPv6 address when connected to an IPv6 network using the Neighbor Discovery Protocol. 

singlemode fiber. Fiberoptic cabling with a narrow core that allows light to enter only at a single angle. Such cabling has higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width (for example, a laser). Also called monomode fiber. 

Simple Network Management Protocol. Network management protocol used almost exclusively in TCP/IP networks. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security. 

shortest path first. Routing algorithm that iterates on length of path to determine a shortestpath spanning tree. Commonly used in linkstate routing algorithms. Sometimes called Dijkstra's algorithm. 

Secure Shell Protocol. Protocol that provides a secure remote connection to a route through a TCP application. 

Secure Shell Protocol version 1. 

Secure Shell Protocol version 2. 

Secure Socket Layer. Encryption technology for the Web used to provide secure transactions, such as the transmission of credit card numbers for ecommerce. 

straight tip. 

Route that is explicitly configured and entered into the routing table. Static routes take precedence over routes chosen by dynamic routing protocols. 

Spanning Tree Protocol. Bridge protocol that uses the spanningtree algorithm, enabling a learning bridge to dynamically work around loops in a network topology by creating a spanning tree. Bridges exchange BPDU messages with other bridges to detect loops, and then remove the loops by shutting down selected bridge interfaces. Refers to both the IEEE 802.1 Spanning Tree Protocol standard and the earlier Digital Equipment Corporation Spanning Tree Protocol upon which it is based. The IEEE version supports bridge domains and allows the bridge to construct a loopfree topology across an extended LAN. The IEEE version generally is preferred over the Digital version. 

A 32bit binary number that is used to define which portion of an IP address refers to the subnet and which portion refers to the host. Sometimes referred to simply as mask. 

switch virtual interface. 

synchronization. 

synchronizationacknowledgment. 

system logging. 

standard terminal emulation protocol in the TCP/IP protocol stack. Telnet is used for remote terminal connection, enabling users to log into remote systems and use resources as if they were connected to a local system. Telnet is defined in RFC 854. 

Telecommunications Industry Alliance. Organization that develops standards relating to telecommunications technologies. Together, the TIA and the EIA have formalized standards, such as EIA/TIA232, for the electrical characteristics of data transmission. 

Transport Layer Security. A future IETF protocol to replace SSL. 

type, length, value. 

Tokenpassing LAN that was developed and supported by IBM. Token Ring runs at 4 or 16 Mbps over a ring topology. Similar to IEEE 802.5. 

type of service 

Time to Live. A mechanism that limits the lifespan or lifetime of data in a computer or network. 

unique device identifier. 

uninterruptible power supply. 

Coordinated Universal Time. Time zone at zero degrees longitude. Formerly called Greenwich Mean Time (GMT) and Zulu time. 

unshielded twistedpair. Fourpair wire medium used in a variety of networks. UTP does not require the fixed spacing between connections that is necessary with coaxialtype connections. Five types of UTP cabling are commonly used: Category 1, Category 2, Category 3, Category 4, and Category 5. 

VLAN ID. The identification of the VLAN, which is used by the standard IEEE 802.1Q. Being 12 bits, it allows for the identification of 4096 VLANs. 

virtual LAN. Group of devices on one or more LANs that are configured (using management software) so that they can communicate as if they were attached to the same wire, when in fact they are located on a number of different LAN segments. Because VLANs are based on logical instead of physical connections, they are extremely flexible. 

variablelength subnet mask. Capability to specify a different subnet mask for the same network number on different subnets. VLSM can help optimize available address space. 

wireless access point. 

Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless communications standards designed to provide up to 1 Gbit/s data rates.