Information Technology Reference
In-Depth Information
following a change. Changes to network name resolution, address space,
and other functions throughout the enterprise should be fully tested, with
adequate time planned to allow cached name resolution entries to expire
before legacy access mechanisms are removed. This is particularly impor-
tant for remote elements of extended enterprise networks.
Inter, Intra, and Extra
The World Wide Web continues to evolve, including new elements and
extending connectivity to an increasingly mobile population. Before I
address mobile computing in greater detail in the next chapter, it is best
to first examine the nomenclature used to define regions of interest in the
extended network.
Terminology for networking often derives from the type of connec-
tivity used to communicate between nodes and the scale of integration
within the network boundary. Common network connectivity catego-
ries include:
• Local Area Network (LAN)—A network comprised of closely con-
nected nodes using smaller packets, facilitating greater numbers of
individual nodes sharing the same transport media. This is typically
the largest level of integration in small- to mid-sized enterprise net-
works, with logical addressing across a single or very small number
of subnets. Smaller companies may find cost savings by licensing a
limited number of publically routed addresses and using an internal
private address space, with some type of network address transla-
tion (NAT) device providing connectivity across the edge boundary.
Networks of this type avoid having to pay for large numbers of pub-
lically routed addresses; typically, only services exposed for public
consumption, such as Web servers, virtual private network gateways,
and locally hosted DNS services, need external addresses.
• Wide Area Network (WAN)—These networks span large geo-
graphic areas using large data packets to facilitate exceptionally
high throughput across very-high-speed connections. Organiza-
tions of mid- to large scale may employ connectivity across WAN
links between remote sites, but typically this is handled by the
Internet service provider (ISP) without direct management within
the enterprise. When using public Internet WAN connectivity, end-
