Chapter 3 - Network Components Flashcards
110 block
Because 66 blocks are subject to too much crosstalk for higher-speed LAN connections, 110 blocks can be used to terminate a cable (such as a Category 5 cable) being used for those higher-speed LANs.
66 block
Traditionally used in corporate environments for cross-connecting phone system cabling. As 10-Mbps LANs started to grow in popularity in the late 1980s and early 1990s, these termination blocks were used to cross-connect Category 3 UTP cabling. The electrical characteristics (specifically, crosstalk) of a 66 block, however, do not support higher-speed LAN technologies, such as 100-Mbps Ethernet networks.
Coaxial cable
Also known as coax, a coaxial cable is composed of two conductors. One of the conductors is an inner insulated conductor. This inner conductor is surrounded by another conductor. This second conductor is sometimes made of a metallic foil or woven wire.
Content engine
A dedicated appliance whose role is to locally cache content received from a remote network (for example, a destination on the Internet). Subsequent requests for that content can be serviced locally, from the content engine, thus reducing bandwidth demand on a WAN.
Content switch
Can be used to load balance requests for content across a group of servers containing that content. If one of the servers in the group needed to have maintenance performed, that server could be administratively removed from the group, as defined on the content switch. As a result, the content switch can help maximize uptime when performing server maintenance. It minimizes the load on individual servers by distributing its load across multiple identical servers. A content switch also allows a network to scale because one or more additional servers could be added to the server group defined on the content switch if the load on existing servers increases.
Domain Name System (DNS) server
Performs the task of taking a domain name (for example, www.ciscopress.com) and resolving that name into a corresponding IP address (for example, 10.1.2.3).
Electromagnetic interference (EMI)
An electromagnetic waveform that can be received by network cable (possibly corrupting data traveling on the cable) or radiated from a network cable (possibly interfering with data traveling on another cable).
Firewall
Primarily a network security appliance, a firewall can protect a trusted network (for example, a corporate LAN) from an untrusted network (for example, the Internet) by allowing the trusted network to send traffic into the untrusted network and receive the return traffic from the untrusted network, while blocking traffic for sessions that were initiated on the untrusted network.
Multilayer switch
Like a router, a multilayer switch can make traffic forwarding decisions based on Layer 3 information. Although multilayer switches more closely approach wire-speed throughput than most routers, routers tend to have a greater feature set and are capable of supporting more interface types than a multilayer switch.
Multimode fiber (MMF)
Multimode fiber-optic cabling has a core with a diameter large enough to permit the injection of light into the core at multiple angles. The different paths (that is, modes) that light travels can lead to multimode delay distortion, which causes bits to be received out of order because the pulses of light representing the bits traveled different paths (and therefore, different distances).
Network as a service (NaaS)
A service provider offering where clients can purchase data services (for example, e-mail, LDAP, and DNS services) traditionally hosted in a corporate data center.
Offsite
The term offsite in the context of virtualization technologies refers to hosting virtual devices on hardware physically located in a service provider’s data center.
Onsite
The term onsite in the context of virtualization technologies refers to hosting virtual devices on hardware physically located in a corporate data center.
Plenum
Plenum cabling is fire retardant and minimizes toxic fumes released by network cabling if that cable were to catch on fire. As a result, plenum cabling is often a requirement of local fire codes for cable in raised flooring or in other open-air return ducts.
Proxy server
Intercepts requests being sent from a client and forwards those requests on to their intended destination. The proxy server then sends any return traffic to the client that initiated the session. This provides address hiding for the client. Also, some proxy servers conserve WAN bandwidth by offering a content caching function. In addition, some proxy servers offer URL filtering to, for example, block users from accessing social networking sites during working hours.
