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Alternates.
Different versions of the same web object. Some origin servers answer requests to the same URL
with a variety of objects. The content of these objects can vary widely, depending on whether a server delivers
content for different languages, targets different browsers with different presentation styles, or delivers
variable content at different times of the day.
ARM.
Adaptive Redirection Module. Used in transparent proxy caching, ARM is a Traffic Server component
that redirects intercepted client traffic destined for an origin server to the Traffic Server application. Before
the traffic is redirected by the ARM, it is intercepted by a Chapter , “L4 switch,” or router.
Cache.
Stores copies of frequently accessed objects close to users and serves them to users when requested.
See also Chapter , “Object store,”.
Cache hierarchy.
Levels of caches that communicate with each other. All cache hierarchies recognize the
concepts of Chapter , “Parent cache,” and Chapter , “Child cache,”.
Cache hit.
An object in the cache that can be served directly to the client.
Cache miss.
An object that is not in the cache or that is in the cache but no longer valid. In both cases, Traffic
Server must get the object from the Chapter , “Origin server,”.
Caching web proxy server.
A web proxy server with local cache storage that allows the proxy to fulfill client
requests locally, using a cached copy of the origin server’s previous response.
CGI .
Common Gateway Interface. A set of rules that describe how an origin server and another piece of
software (a CGI program) located on the same machine communicate.
cgi-bin.
The most common directory name on an origin server in which Chapter , “CGI,” programs are stored.
Child cache.
A cache lower in a Chapter , “Cache hierarchy,” for which Traffic Server is a parent. See also
Chapter , “Parent cache,”.
Cluster.
A group of Traffic Server nodes that share configuration information and can act as a single large
virtual cache.
Configure mode.
One of two modes in Chapter , “Traffic Manager,” and Chapter , “Traffic Line,”. Configure
mode lets you configure the Traffic Server system. See also Chapter , “Monitor mode,”.
Cookie.
A piece of information sent by an origin server to a web browser. The browser software saves the
information and sends it back to the server whenever the browser makes additional requests from the server.
Cookies enable origin servers to keep track of users.
DNS.
Domain Name Service. Traffic Server includes a fast, asynchronous DNS resolver to streamline
conversion of hostnames to IP addresses.
Explicit proxy caching.
A Traffic Server configuration option where client software (typically a browser)
must be specifically configured to send web requests to the Traffic Server proxy.
FTP.
File Transfer Protocol. A protocol based on TCP/IP for reliable file transfer.
Full clustering.
A Traffic Server cluster distributes its cache across its nodes into a single, virtual object store,
rather than replicating the cache, node by node. See also Chapter , “Management-only clustering,”.
HTTP.
HyperText Transfer Protocol. The client-server protocol upon which the World Wide Web is based.
ICP.
Internet Cache Protocol. A protocol for proxy caches to exchange information about their content.
IP.
Internet Protocol. The lowest-layer protocol under TCP/IP responsible for end-to-end forwarding and long
packet fragmentation control.
ISP.
Internet Service Provider. An organization that provides access to the Internet.
JavaScript.
A network-oriented programming language specifically designed for writing programs that can
be safely downloaded to your computer through the Internet.
L4 switch.
An ethernet switch that can control network traffic flow using Level 4 rules. The switch can
intercept desired client protocol packets and direct them to a proxy for transparent operation.
Glossary