Technical data

server returns a nonauthoritative answer when the server’s answer comes from
its own cache.
autonomous confederation
A group of independent computer systems that trust each other regarding routing
and reachability information; members believe information provided by other
members in preference to information received from systems that are not part of
the confederation.
autonomous system (AS)
A collection of networks controlled by one administrative authority. The gateways
within this system are expected to trust one another and to share and update
routing information among themselves by any mutually agreeable protocol. A
core gateway must also be designated to share routing information with other
autonomous systems by means of an External Gateway Protocol. See also
External Gateway Protocol.
A set of routers under a single technical administration, using an interior gateway
protocol and common metrics to route packets within the AS, and using an exterior
gateway protocol to route packets to other ASs. Since this classic definition was
developed, it has become common for a single AS to use several interior gateway
protocols and sometimes several sets of metrics within an AS.
The use of the term autonomous system stresses that even when multiple internal
gateway protocols and metrics are used, the administration of an AS appears to
other ASs to have a single coherent interior routing plan and presents a consistent
picture of what networks are reachable through it. The AS is represented by
a number between 1 and 65534, assigned by the Internet Assigned Numbers
Authority.
automounting
The process of mounting NFS file systems on an as-needed basis. The NFS file
system automatically unmounts after a period of inactivity on the file system.
(The default is 5 minutes.) You specify file systems to be automounted in the
automounts
map file.
auxiliary server
The Compaq TCP/IP Services for OpenVMS software that runs as a background
process and listens for incoming requests for services. When it receives a request,
it runs the appropriate server application; includes
inetd
, security, and logging
options.
availability
The proportion of time a specific piece of equipment, system, or network is usable,
compared to the total time it is expected to be.
backbone
The primary connectivity mechanism of a hierarchical distributed system. Usually
a high-speed high-performance network that links together other networks into
an internetwork. All systems with connectivity to an intermediate system on the
backbone will connect to each other. This does not prevent systems from setting
up private arrangements with each other to bypass the backbone for reasons of
cost, performance, or security.
background mounting
In the UNIX environment, the default mount option is to retry remote mount
requests in the foreground. If during a boot process, any server listed in
/etc/fstab
is not currently available, the local system will not finish booting
until the server becomes available. With background mounting, a remote mount
Glossary–5