In standard DNS, an authoritative DNS nameserver is one that has knowledge of the DNS domain to which the origin server belongs.
In GRM deployments, GRM DNS servers interact with authoritative DNS nameservers to resolve DNS queries for unrecognized domains and to perform other functions, such as zone transfers.
In the context of GRM, the GRM DNS server can appear to be the authoritative DNS server for a content provider if a GRM DNS server takes over DNS for the existing CDN namespace. In this case, the GRM DNS server assumes the identity of the authoritative DNS nameserver (hereafter referred to as the back-end DNS nameserver), and subsequently resolves all DNS queries for domains associated with the CDN namespace. DNS queries for non-CDN domains and other DNS operations are proxied through the GRM DNS server to the back-end DNS nameserver.
The authoritative DNS nameserver for the CDN. The GRM DNS server must use the back-end DNS nameserver to resolve DNS queries for non-CDN domains and to perform other DNS operations. These operations are proxied through the GRM DNS server to the back-end DNS nameserver.
The process by which a NetCache appliance receives a request for an object and can resolve the request from its cache rather than having to fetch the object from the origin server.
The process by which a NetCache appliance receives a request for an object but that object is not in the cache. The NetCache appliance then attempts to fetch the object from the origin server.
A canonical name (CNAME) is the host name of the device as specified in a DNS A record. Specifying a canonical name allows multiple aliases to be associated with a single name. See also CNAME record.
Network appliances on which the GRM agent software is enabled that have been identified in the GRM server configuration as a center cache. Edge caches are located in edge groups, such as POPs, close to end users. Edge caches in a particular edge group serve only the clients associated with that edge group. That is, when a client in a specific edge group makes a request or DNS query, the GRM server does not return IP addresses of edge caches in a different edge group.
See Classless Inter-Domain Routing.
Classless Inter-Domain Routing (CIDR) eliminates the concept of class A, B, and C networks and replaces them with a generalized IP prefix. A CIDR address includes the standard 32-bit IP address and also information on how many bits are used for the network prefix. For example:
172.200.0.0/16
In the preceding example, the /16 indicates that the first 16 bits of the IP address are used to identify the unique network--the remaining bits identify the specific host.
Canonical Name Record. A CNAME record creates an alias of a canonical name. The CNAME alias gains all properties of the original, including IP addresses. Because of this, no other record should have the same name that appears in a CNAME record.
See also canonical name.
A network service provider that distributes content and services to optimize content delivery and charges a fee to do so.
A command line tool for querying DNS servers. Similar to nslookup. See also nslookup.
Domain Name Service (DNS) is the standard mechanism on the Internet for advertising and accessing a variety of information about computer hosts. DNS handles mapping between host names, which humans find convenient, and Internet addresses, which computers require. DNS makes host information available throughout the Internet, distributed among many sites and organizations, not just in a single central site.
Network appliances on which the GRM agent software is enabled that have been identified in the GRM server configuration as an edge cache. Edge caches are located in edge groups, such as POPs, close to end users. Edge caches in a particular edge group serve only the clients associated with that edge group. That is, when a client in a specific edge group makes a request or DNS query, the GRM server does not return IP addresses of edge caches in a different edge group.
A group, such as a POP, in which edge caches are located. Edge groups are identified in the GRM server configuration.
Edge caches in a particular edge group serve only the clients associated with that edge group. That is, when a client in a specific edge group makes a request or DNS query, the GRM server does not return IP addresses of edge caches in a different edge group.
A generic term to refer to NetCache appliances on which the GRM agent software is enabled. In the GRM server configuration, a cache on which the GRM agent software is installed can be identified as a center cache or an edge cache.
A NetCache appliance located in a CDN data center that is configured as a GRM server. You can configure a GRM server as a GRM DNS server (for DNS-based redirection services) or a GRM L7 server (for application-level (L7) redirection services).
Switches typically include multiple methods for handling traffic. When this guide refers to L4 or L7 switches, it refers to a feature on a switch that can support transparent proxying; that is, a feature that operates on the L4 or L7 layer of the OSI model. Switch names vary by vendor.
The streaming media control protocol used in Windows Media 3 & 4 streams.
See Microsoft Media Streaming.
Standard tool for querying nameservers in command line operating systems, for example, UNIX and LINUX.
An open standard for delivery of real-time media over the Internet. See also streaming media.
See Real Time Streaming Protocol.
A term used to describe media files that begin playing while they are being transmitted over the network to the media player on the client computer. In contrast, conventional Web files must be downloaded entirely before the user can view them. Commonly requested types of streaming media are video and audio. Streaming media also includes interactive media, cartoon-like animations, panoramic data, and more.
A specially configured NetCache appliance that intercepts client requests for streaming media (RTSP, MMS, or both). When a streaming media cache is deployed between clients and a streaming media server, streaming requests that would otherwise have been sent directly to the streaming server are sent to the cache. For live streaming media presentations, bandwidth savings are realized when multiple clients request the same unique stream. NetCache caches on-demand media streams. See also streaming media.
A method for providing access to NetCache appliances in which users do not have to manually configure Web browsers or media players for requests to be sent to the NetCache appliances. Transparent proxying is typically deployed with an L4 switch, and L7 switch, or a WCCP router. Less commonly, it is deployed with a policy-based router.
Uniform Resource Locator. To find a Web resource, you enter a name called a URL in the Location field of your Web browser, for example, http://www.netapp.com/.
A Cisco router running WCCP 2.0 software.
A NetCache appliance configured as an intermediary server that accepts requests from clients and forwards them to a Web server or, if appropriate, services the requests from its own cache. A Web cache acts as an agent for the client browser. A NetCache appliance configured as a Web cache handles any or all of HTTP, FTP, Gopher, and Tunnel (for example, HTTPS and SSL) requests.
A special type of query in which the entire contents of a zone are requested from a nameserver. (DNS namespaces are divided up into zones, which store name information about one or more DNS domains.) Secondary DNS nameservers update locally stored zone information by requesting zone transfers from primary DNS nameservers.
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Part No. 210-00374
File: glossary.htm
Last updated: 11/12/02 17:45:19