Network Terms "R"

Network Glossary and acronym's

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

RADIUS (Remote Authentication Dial-in User Service)

RADIUS (Remote Authentication Dial-In User Service) is primarily used for pre-authenticating remote clients before access to the network is granted. RADIUS maintains client profiles in a centralized database. It offloads the authentication burden for dial-in users from the normal authentication of local network clients. For environments with a large number of dial-in clients, RADIUS provides improved security, easier administration, improved logging, and less-performance impact on LAN security systems.

The primary benefit of RADIUS (Remote Authentication Dial-In User Service) can be summarized as centralized. RADIUS is a centralized database of user access profiles. User access profiles determine the rules and restrictions dial-in users must comply with to establish a dial-up link to the network. Only after satisfying the criteria enforced by RADIUS is a remote client granted access to the network.

RAID (Redundant Array of Inexpensive Disks)

A method of categorizing the use of multiple disks to provide performance enhancement and/or fault tolerance.

RARP (Reverse Address Resolution Protocol)

With a given host name, the RARP request will discover the IP address on a network.

RAS (Remote Access Service)

A Windows NT service that you install on one of your network's servers to allow clients to access your network remotely. The RAS software can manage up to 256 simultaneous remote connections.

RCONSOLE

A GSNW or CSNW utility that allows you to view and perform console functions on a remote NetWare system console.

RDISK

A Windows utility that you can use to restore the hard disk configuration and to update a Emergency Repair Disk.

Reciprocal replication

The process of a domain controller pulling updates from its replication partner as well as pushing updates to its replication partner. In comparison, each replication partner typically pulls updates from its partner.

Recomputation

Recomputation is the process of a router comparing routes in search for a new successor route. Recomputation occurs when a successor route to a destination goes down and there are no feasible successors for the destination.

Record

An entry in a DNS name server is known as a record.

In SQL Server, a record is a set of related fields (columns) of data joined as a unit. In a SQL database, it is more common to talk about rows and columns than records and fields.

Recursive query

In a recursive query, a name server uses its own resources to resolve the request. A client sends a name resolution request to a server. If it has the information, it sends the results back to the client. If it does not have the information, it passes the request to another server. A server can answer a recursive request with either the requested information or an error message. It cannot refer the client to another server.

Redirector

A file system driver that receives I/O requests for network resources and send the requests into the network. For example, a redirector redirects print jobs away from the client computer's printer port and out to the network.

Reduced Instruction Set Computing (RISC)

A RISC computer has a microprocessor that performs a small subset of instructions. This lets it process data more quickly.

Redundancy

Redundancy is the implementation of one or more backup components that perform duplicate functions. Redundancy:

Improves system performance.
Allows a system to keep functioning normally in the event of a component failure.
Increases fault tolerance.

Redundant Array of Inexpensive Disks (RAID)

A method of categorizing the use of multiple disks to provide performance enhancement and/or fault tolerance.

REG_

Prefix for Registry data types REG_BINARY, REG_DWORD, REG_EXPAND_SZ, REG_MULTI_SZ, AND REG_SZ.

Registry

A unified database in which Windows 2000 stores all hardware and software configuration information for the local computers.

Registry Editor

A Windows utility you can use to display, troubleshoot, and manually edit the contents of the registry.

Regular area

A regular area (also known as nonbackbone area)does not allow traffic to pass through it. The regular area's primary function is to connect users and resources.

Rehoming

Rehoming is the process of moving a public folder from one server to another.

Relational database

A collection of units of data stored in tables that represent a group of objects (for example, Empoyees, Products, or Customers). Columns in a table represent an attribute of the object (for example, an attribute of an Employee might be LastName, or an attribute of a Product might be shipping weight). Each row in a table represents a single instance of that kind of object (for example, the employee name Jane Smith or the part number 3Y557). Data from one table can be used to find related data in another.

Relational database management system (RDBMS)

Software used to store, update, and retrieve data. It has a client/server architecture, stores data in tables with rows (records) and columns (fields), defines and enforces relationships among data items, and uses some version of Structured Query Language (SQL).

Relay domain

A relay domain is a domain for which a server accepts mail but is not authoritative.

Reliable Transport Protocol (RTP)

Reliable Transport Protocol (RTP) is used by EIGRP to deliver packets to neighboring routers in a guaranteed, ordered manner. RTP:

Supports intermixed transmission of unicast or multicast packets.
Only reliably sends certain EIGRP packets.
Sends hello packets that contain an indicator as to whether or not the packet needs to be acknowledged by the recipient.
Ensures low convergence time by sending packets even when unacknowledged packets are pending.

Remote access

In a broad sense, remote access is access to a local area network from home or some other place that is not directly connected to the LAN. More specifically, remote access is remote networking for mobile workers or system administrators who manage servers at multiple location. Windows 2000 and Network and Dial-up Connections let users access networks remotely for such services as file and printer sharing, electronic mail, and database access. Remote access is part of the integrated Routing and Remote Access service.

Remote Access Admin

An Windows NT utility used to configure a RAS server. This utility can also be used to start a RAS server.

Remote Access Service (RAS)

A Windows NT service that you install on one of your network's servers to allow clients to access your network remotely. The RAS software can manage up to 256 simultaneous remote connections.

Remote Authentication Dial-in User Service (RADIUS)

Remote delivery queue

Remote delivery queues hold messages that will be delivered using SMTP to recipient mailboxes that reside on remote servers in Exchange 2007. Each remote delivery queue holds messages that are routed to recipients with the same delivery destination. Each time multiple recipients have the same delivery destination, a remote delivery queue is dynamically created. Once the messages have been successfully delivered, the queue expires and is automatically deleted three minutes later.

Remote Execution (REXEC)

A Windows utility that lets you run a process on a remote computer.

Remote network backup

A backup method that uses a tape drive installed on a single server or workstation to back up data other servers and computers connected to the network. This method backs up the registry on the computer attached to the tape drive, but not the registries of the other computers.

Remote Procedure Call (RPC)

Remote Procedure Calls are based on a client/server model in which one server runs processes on another server. Both servers assume the calls are local, when in reality they run over LAN connections and through software libraries on both servers.

Remote Shell (RSH)

A Windows NT utility that lets you run commands on a UNIX host.

Rendezvous Point (RP)

A Rendezvous Point (RP) is a temporary connection between a multicast receiver and an existing shared multicast tree. When a volume of traffic crosses a threshold, the receiver is joined to a source-specific tree, and the feed through the RP is dropped.

Repadmin.exe

A command-line Windows 2000 support tool that lets you perform replication-related tasks.

Repeater

A device that reamplifies packets sent on a network. A repeater provides additional distance on a network by reamplifying packets and sending them on.

Replica

A copy of the data in a directory partition or shared folder.

Replicated update

An update to the Active Directory update that is made through replication. For example, if BSmith's password is changed on Server1 then replicated to Server2, the replicated update was made on Server1.

Replication

A process by which a collection data is copied to one or more computers in order to create synchronized sets of data. Changes to Active Directory, for example, are regularly replicated to all domain controllers in a forest.

Replication latency

The time period between when a change is made to a server's directory and when that change appears on other servers in the same site. It is usually 5 minutes.

Replication Monitor

Replmon.exe. A graphical Windows 2000 support tool that lets you monitor the replication process and perform replication-related tasks.

Replication partner

One of two domain controllers that exchange updated information.

Replication topology

The series of connections over which replication takes place.

Replicator

A local group used by the Directory Replicator service. This group is not used for administration.

Request for Comment (RFC)

A series of documents regarding TCP/IP standards. RFCs describe the internal workings and processes of the Internet. TCP/IP standards, however, are developed by consensus. Member of the Internet Society can submit a document to be published as an RFC. After submittal, the document is reviewed for technical accuracy and assigned a classification. There are five classifications of RFCs, including Required, Recommended, Elective, Limited Use, Not Recommended. If a document is being considered as a standard, it goes through stages known as maturity levels. These levels include proposed standard, draft standard, and Internet standard.

Reservation

A specific IP address permanently set aside for use by a specific DHCP client. Addresses are reserved in the DHCP database by using DHCP Manager. Each reserved address is associated with a unique client device identifier.

Resolver

A client computer running DNS that queries a DNS server on the network for name resolution.

Resource

Any network service, such as file and print are resources. Microsoft provides many resource types, including DHCP server, file shares, print spooler, and so on.

Resource mailboxes

Resource mailboxes are used to manage meeting rooms, projectors, and additional facilities in Exchange 2007. When a resource mailbox is created, a disabled user account is created for the mailbox. Rights are then designated to a user who will manage the resource mailbox, or rules are created for the mailbox so it can manage itself.

Resource records

A DNS record that is to be placed in the name service. Using the DNS Manager, you can configure new host records and new resource records.

Retransmit Time-Out (RTO)

Retransmit Time-Out (RTO) is the amount of time in milliseconds that a router will wait for an acknowledgement before sending a reliable packet to a neighbor from the retransmission queue.

Reverse Address Resolution Protocol (RARP)

With a given host name, the RARP request will discover the IP address on a network.

Reverse lookup

A lookup capability provided by DNS that allows a resolver to provide an IP address and request a matching host name. Some applications provide the ability to implement security based on connecting host names. When a request is made to access a particular application, the application can contact the DNS server and do a reverse lookup on the client's IP address. If the host name returned by the DNS server is not in the access list for the NFS volume, or if the host name was not found in DNS, then the request would be denied.

Reverse Path Forwarding (RPF)

Reverse Path Forwarding (RPF) routes traffic away from the source rather than to the receiver.

REXEC (Remote Execution)

A Windows utility that lets you run a process on a remote computer.

RFC (Request for Comment)

RFC editor

A person who has the responsibility to review an RFC submitted for publication and assign a classification to the document. See RFC for information on classifications and maturity levels for RFCs.

Rights

Rights allow you to carry out specific tasks in Windows 2000. For example, with Backup Operator, you can back up and restore user and system state data on a Windows 2000 computer.

Ring

A ring topology connects neighboring nodes until they form a ring. Signals travel in one direction around the ring. In ring topologies, each device on the network acts as a repeater to send the signal to the next device. With a ring:

Installation requires careful planning to create a continuous ring.
Isolating problems can require going to several physical locations along the ring.
A malfunctioning node or cable break can prevent signals from reaching nodes further along on the ring.

Ring wrapping

A technique for rerouting data on an FDDI ring network to a secondary ring to prevent a break in the network from interrupting network service. Also referred to as dual counter-rotating rings.

RIP (Routing Information Protocol)

A protocol that allows a router to communicate routing information to another router on the network.

RIPX (Routing Information Protocol over IPX)

A protocol that routers use to exchange information between other routers on an IPX network and that hosts use to decide on the best route when forwarding remote IPX traffic.

RISC (Reduced Instruction Set Computing)

A RISC computer has a microprocessor that performs a small subset of instructions. This lets it process data more quickly.

Roaming user profile

A user profile located on the server but downloaded to the local computer when the user logs on. Changes to the profile are saved both locally and on the server when the user logs off.

Roaming user profiles are convenient for users that move from location to location and use different computers, but want to keep the same desktop. The profile defines their desktop and will be downloaded to the computer when the user logs in.

Robot

A program that explores links inside and outside a Web site. Also called a spider.

Rogue DHCP Server

A rogue DHCP server is an unauthorized DHCP server on the network.

Root authority

A certification authority that has no higher authority to vouch for it. The root authority is at the top of a certification hierarchy.

Root certificate

A certificate that is digitally signed by the authority that issued it. This occurs when the issuing authority is the root authority and there is no higher authority to verify the certificate.

Root directory

The first-level directory on a hard disk or partition.

ROUTE

A Microsoft utility that views or modifies the local routing table in a TCP/IP network.

Route aggregation

Route aggregation allows the aggregation of specific routes into a single route in BGP. When route aggregation is implemented without any modifiers, granularity is lost because there is no inheritance of the individual route attributes (such as AS_PATH or community).

Route convergence

The process by which routers exchange route information between themselves. Each routing table entry learned through RIP is given a time-out value of three minutes past the last time it was last received in a RIP advertisement.

Route map

A route map is an access list that has the ability to apply logic and make modifications to parameters by using route map statements. Route maps are best used in:

PBR
NAT
BGP
Route filtering during redistribution

Route poisoning

Using the split horizon with poison reverse method (also called poison reverse or route poisoning), routers continue to send information about routes back to the next hop router, but advertise the path as unreachable. If the next hop router notices that the route is still reachable, it ignores the information. If, however, the path timeout has been reached, the route is immediately set to unreachable (16 hops for RIP).

Route redistribution

Route redistribution is the capability of boundary routers connecting different routing domains to exchange and advertise routing information.

Route summarization

Route summarization is the consolidation of multiple routes into a single advertisement.

Router

A device that receives packets, reads their headers to find addressing information, and sends them on to their correct destination on the network or Internet.

Routing Information Protocol (RIP)

A protocol that allows a router to communicate routing information to another router on the network.

Routing Information Protocol over IPX (RIPX)

A protocol that routers use to exchange information between other routers on an IPX network and that hosts use to decide on the best route when forwarding remote IPX traffic.

Routing table

A table that gives network bridges and routers the information needed to forward data packets to locations on other networks. Routing tables must be updated frequently as changes to machines and connections occur.

Routing tables include network addresses, the subnet mask, and the gateway addresses. They may also include the subnet broadcast address, network broadcast address, local loopback address, local network address, and the local host address.

RP (Rendezvous Point)

RPC (Remote Procedure Call)

RPF (Reverse Path Forwarding)

Reverse Path Forwarding (RPF) routes traffic away from the source rather than to the receiver.

RSH (Remote Shell)

A Windows NT utility that lets you run commands on a UNIX host.

RTO (Retransmit Time-Out)

Retransmit Time-Out (RTO) is the amount of time in milliseconds that a router will wait for an acknowledgement before sending a reliable packet to a neighbor from the retransmission queue.

RTP (Reliable Transport Protocol)

Reliable Transport Protocol (RTP) is used by EIGRP to deliver packets to neighboring routers in a guaranteed, ordered manner. RTP:

Supports intermixed transmission of unicast or multicast packets.
Only reliably sends certain EIGRP packets.
Sends hello packets that contain an indicator as to whether or not the packet needs to be acknowledged by the recipient.
Ensures low convergence time by sending packets even when unacknowledged packets are pending.

Run

A Windows utility that is used to start applications.