Glossary

An action is invoked when an event handler is triggered as the result of a particular event occurring. Possible actions include writing to log files, sending an email message, sending a SYSLOG message or SNMP trap, or running a custom action program.

The process that serves the Web-based Admin UI, and handles configuration and status communications between the core Virtual Traffic Manager software, the Admin UI, and all product APIs.

The Virtual Traffic Manager's audit log of users' activities for the Virtual Traffic Manager. These can be viewed within the Diagnose pages.

The IP address which a Virtual Traffic Manager machine uses to communicate with a back-end server, or the IP address of a back-end server.

A machine which runs a service, such as a Web or mail server. A back-end server is typically within your local network, and requests handled by the Virtual Traffic Manager are passed on to it. A back-end server together with a specified port forms a node in the Virtual Traffic Manager.

The ability to monitor and control the amount of network bandwidth available to a particular service or type of request.

A central repository for objects which you can apply to your services. There are catalogs for rules, monitors, service protection classes and various SSL items.

A recognized authority which independently signs SSL certificates.

A list of client SSL certificates which should be considered invalid; issued by a certificate authority.

A request created from a self-signed certificate. You can submit the CSR to a certificate authority for them to sign.

A Classless Inter-Domain Routing (CIDR) IP subnet includes a standard 32-bit IP address and additional information on how many bits are used for the network prefix. For example, in the CIDR IP subnet "10.13.1.48/22", the "/22" indicates that the first 22 bits are used to identify the unique network prefix and the remaining 10 bits identify the specific host. Alternatively, the Virtual Traffic Manager allows to specify a CIDR IP subnet using a subnet mask "10.13.1.48/255.255.255.0" or explicitly "10.13.1.".

An SSL certificate held by a client, granting the client access to a restricted site.

A group of Virtual Traffic Managers which share the same configuration.

The script which must be run after installing and before starting the Virtual Traffic Manager. It deals with fundamental settings such as passwords and specifying whether the Virtual Traffic Manager should stand alone or join an existing cluster.

A small item of data given to a client by a server that is stored either on the client's file system or in the browser client session. The client stores the data and provides it to the server on subsequent requests. Cookies are used to track client data such as session persistence maps.

A malicious attempt to prevent legitimate use of a service, often by flooding a network or disrupting connectivity between machines.

The section of the Admin UI that helps you diagnose and fix any faults with your Virtual Traffic Manager setup.

A node in a pool that is not used; it is not monitored, and no traffic is sent to it. Disabling a node is an alternative to removing the node from the pool, but disabling it allows it to be reinstated more easily.

A Denial of Service attack which comes from a group of machines; these machines have often been compromised by worms or viruses.

The demilitarized zone for a firewall. This zone sits between the internal network and the Internet, and often holds your externally available servers.

A node in a pool which is being sent no new connections. When all existing connections and sessions to this node have expired, it can be removed from the pool safely.

A file sent to the client when no nodes are available to respond to its request. Error files are set up on a per-pool basis.

An event is raised when a particular change or occurrence takes place, such as an IP Address transfer or a node failure or recovery. All events are logged to the global Event Log.

An event hander configures the actions that the Virtual Traffic Manager should take when an event in the associated Event Type occurs.

The Virtual Traffic Manager’s log of events within the Virtual Traffic Manager. These are graded as INFO, WARN, SERIOUS, FATAL etc, and can be viewed within the Diagnose pages.

A set of events, grouped for administrative convenience. When any event in a particular event type occurs, the Virtual Traffic Manager can run the actions associated with that event type.

The act of taking on a failed machine’s load by other machines in the cluster.

If all the nodes in a pool should fail, requests will be sent to its failure pool, if one is configured.

The ability of a cluster or pool to cope with failure of one or more of its servers, without interruption to service.

The permanent, externally available IP address of a Virtual Traffic Manager.

A server which is contactable from the Internet, such as a Virtual Traffic Manager.

The process by which the Virtual Traffic Manager tracks the health of Virtual Traffic Managers and back ends, so that requests will not be sent to a failed machine.

A network layer protocol that is expected to supersede the current protocol, IPv4. Its features include a bigger range of addresses, higher security and further advantages.

Java Extensions can increase (“extend”) the capabilities of TrafficScript. A TrafficScript rule (or RuleBuilder rule) can invoke a Java Extension to process a request or response, and the Java run-time environment provides a much more powerful set of programming language tools and libraries than TrafficScript does alone.

The distribution of requests among a number of back-end servers, so that every request is dealt with as quickly as possible.

In cryptography, MD5 (Message-Digest algorithm 5) is a widely used cryptographic hash function with a 128-bit hash value. As an Internet standard (RFC 1321), MD5 has been employed in a wide variety of security applications, and is also commonly used to check the integrity of files.

Multipart Internet Mail Extension, a name which identifies the type of data being transferred. For example, “application/pdf” for PDF files. This standard was first used in email applications, and has been widely adopted by other Internet technologies such as Web servers.

A regular test which the Virtual Traffic Manager uses to track the health of a pool.

A server that implements a name service protocol. For example, a Domain Name System (DNS) server might translate the domain name www.example.com to the IP address 208.70.196.59.

Network address translation (NAT, also known as network masquerading) involves rewriting the source or destination addresses of IP packets as they pass through a router or firewall. Most systems using NAT do so in order to enable multiple hosts on a private network to access the Internet using a single public IP address.

A back-end server with an associated port, which receives requests sent to it by the Virtual Traffic Manager and responds with the requested content.

Private Enhanced Mail. The .pem file extension is used for Base 64-encoded X.509 keys and certificates. These are printable text, and start with a line of the form: ----- BEGIN CERTIFICATE -----

The standard used to communicate with secure hardware.

A logical group of nodes. When a virtual server assigns requests to a pool, it load-balances them across the nodes.

Settings for managing the connection between a remote client and a virtual server, or between a pool and its nodes.

An application-level protocol that enables on-demand delivery of real-time data, such as audio and video formats, using the TCP and UDP protocols.

A UDP packet format for delivering audio and video files, which is commonly used alongside RTSP to provide the delivery of the streaming data.

A TrafficScript or RuleBuilder rule that controls how the Virtual Traffic Manager should handle a request. Rules are invoked by a virtual server, and can inspect, manipulate, rewrite and route requests; they can also control how other capabilities in the Virtual Traffic Manager are used to manage the request.

the counterpart of request rules, response rules control how the Virtual Traffic Manager should handle a response.

A visual editor for creating rules, which allows you to select conditions on the request to be examined, and actions that follow if any or all of these conditions are met.

An SSL certificate signed by its owner, rather than a certificate authority. These are useful for security testing but should not be used for live sites. You can issue a certificate signing request to convert your certificate to one signed by a certificate authority.

An SSL certificate used to identify an SSL service (such as a Web site), and containing the public key necessary to set up the encrypted transaction.

Common Internet services include Web, mail, DNS and applications such as .NET and SOAP. They are provided, publicly or locally, through an IP or DNS address and port combination.

The ability to monitor back-end server response times, compare them to a conformance value and react to changes, including dynamically adjusting the resources available.

The protection of your Internet services from attacks such as denial of service (DoS) and distributed denial of service (DDoS).

A group of service protection settings you define. The class is held in the Service Protection Catalog and can be applied to any virtual server.

A protocol used in Internet for conferencing, telephony, presence, events and instant messaging.

A process by which requests belonging to the same user session are always sent to the same node. Sessions can be identified by several methods including IP addresses, cookies or SSL session IDs.

Simple Network Management Protocol, an open standard for network monitoring and management. It allows you to monitor devices on a network and gather performance data.

Simple Object Access Protocol, an XML-based standard for Web services messages.

Secure Sockets Layer, a protocol which provides encrypted communications over a network. Requests can be decrypted and re-encrypted within the Virtual Traffic Manager.

A file in the tar file format, a standard type of archive file format. It is used widely to archive and unarchive files while preserving file system information such as user and group permissions, dates, and directory structures.

An IP address you use to publish an Internet service, usually linked to your public DNS entry.

A logical group containing several traffic IP addresses, and spanning some or all of your Virtual Traffic Managers. These Virtual Traffic Managers negotiate to ensure that the IP addresses in the group are always available.

A front-end server running the Virtual Traffic Manager and managing your services.

The ability to deploy unlimited numbers of active and passive Virtual Traffic Managers, providing resilience to multiple failures and the ability to scale the Virtual Traffic Manager cluster as the need arises. Also known as N+M Redundancy.

The scripting language used to write rules for the Virtual Traffic Manager range of solutions.

The means or vehicle by which a Denial of Service or Distributed Denial of Service attack is made.

An interface between the Virtual Traffic Manager and the Internet. A virtual server manages one of your services. It receives a request from the Internet and, possibly after SSL-decrypting it and applying rules, assigns it to a pool.

Extensible Markup Language, used for storing and exchanging structured data.

A language for addressing parts of an XML document. It can be used in conjunction with TrafficScript rules to make decisions based on the document’s content.