Glossary
R
153 terms.
- RA-Guard
A layer-2 filtering technique that blocks rogue Router Advertisement messages before they reach hosts. It is meant to stop attack packets at a switch.
Like I'm five A guard at the door of the street who stops fake road signs from getting in.
- RADIUS
Remote Authentication Dial In User Service. A protocol in which an access device asks a central server whether a user may connect and what service to give them.
Like I'm five A door guard phoning the main office to ask whether a visitor is allowed in.
Used in RFC 1492 RFC 2058 RFC 2059 RFC 2139 RFC 2194 RFC 2477 RFC 2486 RFC 2548 RFC 2607 RFC 2618 RFC 2619 RFC 2620 RFC 2621 RFC 2809 RFC 2865 RFC 2866 RFC 2867 RFC 2868 RFC 2869 RFC 2882 RFC 2888 RFC 2924 RFC 2989 RFC 3127 and 122 more
- RARP
The Reverse Address Resolution Protocol. A host that knows only its hardware address asks a server for its IP address. Superseded in practice by BOOTP and DHCP.
Like I'm five A computer shouting its name tag number and waiting for someone to tell it its address.
Used in RFC 903 RFC 906 RFC 917 RFC 950 RFC 951 RFC 1060 RFC 1123 RFC 1201 RFC 1294 RFC 1490 RFC 1497 RFC 1700 RFC 1931 RFC 2067 RFC 2390 RFC 2427 RFC 4391 RFC 4392 RFC 7961 RFC 8171 RFC 8302
- RARP server
A host that keeps a table of hardware addresses and the IP addresses assigned to them, and answers RARP requests from other hosts on its network segment.
Like I'm five The office clerk with the list of which name tag belongs to which address.
Used in RFC 903
- Rate limiting
Capping how many requests a client may make in a period of time. HTTP signals it with 429 Too Many Requests.
Like I'm five A rule that says, 'only so many knocks per minute'.
Used in RFC 998 RFC 2505 RFC 2644 RFC 2697 RFC 2813 RFC 2859 RFC 3694 RFC 3738 RFC 3871 RFC 4111 RFC 4286 RFC 4631 RFC 4657 RFC 4706 RFC 4732 RFC 5085 RFC 5158 RFC 5428 RFC 5860 RFC 5920 RFC 6192 RFC 6374 RFC 6398 RFC 6425 and 68 more
- Raw public key
A bare public key sent in a TLS handshake instead of a full X.509 certificate, so no certificate chain or authority is involved.
Like I'm five Showing just the key itself instead of a full ID card with stamps on it.
- RBridge
A device that implements the TRILL protocol. The terms RBridge and TRILL switch mean the same thing.
Like I'm five A smart network switch that finds good paths for messages.
Used in RFC 6905 RFC 7172 RFC 7175 RFC 7176 RFC 7177 RFC 7455 RFC 7780 RFC 7781 RFC 7782 RFC 7783 RFC 7956 RFC 7968 RFC 7978 RFC 8139 RFC 8171 RFC 8302 RFC 8361 RFC 8380 RFC 8383 RFC 8384 RFC 8397 RFC 9183 RFC 9600
- RBridge Channel
A TRILL facility for carrying control messages between RBridges as TRILL Data packets. Each kind of message has a protocol number in an IANA registry.
Like I'm five A private mail lane that bridges use to send notes to each other.
- RCODE
The response code field in a DNS message header. It reports whether the query succeeded, for example NOERROR or Name Error (NXDOMAIN).
Like I'm five A little status word on the answer: fine, or what went wrong.
Used in RFC 1035 RFC 2136 RFC 2308 RFC 2671 RFC 2845 RFC 4074 RFC 4408 RFC 5395 RFC 6672 RFC 6891 RFC 6895 RFC 8490 RFC 8765 RFC 8906 RFC 8914 RFC 8945 RFC 9499 RFC 9619 RFC 9664 RFC 9665 RFC 10029
- RDAP
The Registration Data Access Protocol, an HTTP-based protocol that returns registration data as JSON objects.
Like I'm five A way to ask a website who is registered as the owner of a name or number and get a tidy answer.
Used in RFC 7480 RFC 7481 RFC 7484 RFC 7485 RFC 8056 RFC 8521 RFC 8605 RFC 8977 RFC 8982 RFC 9082 RFC 9083 RFC 9536 RFC 9537 RFC 9560 RFC 9910
- RDMA
Remote Direct Memory Access, a technique for moving data efficiently between computers by having network hardware place it directly into destination buffers in memory.
Like I'm five A way for one computer to put data straight into another computer's memory without bothering its processor.
Used in RFC 5040 RFC 5043 RFC 5044 RFC 5046 RFC 5047 RFC 6581 RFC 7145 RFC 7306 RFC 7609 RFC 8166 RFC 8167
- Real-time text
Text that is transmitted instantly as it is typed or created, so recipients can read a message while it is still being written.
Like I'm five Chat where you see the other person's letters appear as they type.
- Realm
A Kerberos administrative domain with its own KDC and principal database. Realm names conventionally look like an upper-case DNS name such as EXAMPLE.COM.
Like I'm five One club with its own member list and its own helper.
Used in RFC 1510 RFC 1964 RFC 2069 RFC 2194 RFC 2486 RFC 2607 RFC 2617 RFC 2663 RFC 2712 RFC 2809 RFC 2865 RFC 3102 RFC 3103 RFC 3104 RFC 3235 RFC 3579 RFC 3588 RFC 3846 RFC 4004 RFC 4120 RFC 4282 RFC 4556 RFC 5021 RFC 5179 and 34 more
- Reassembly buffer
Storage space in an IMP used to hold packets of a multi-packet message until all packets arrive and the complete message is reassembled.
Like I'm five A temporary holding area where the network reassembles messages that arrived in pieces.
- Receive window
The 16-bit Window field a TCP endpoint advertises to say how many more bytes it is currently willing to accept, which limits how much the peer may send at once.
Like I'm five How much room is left on your friend's desk for new pages.
Used in RFC 793 RFC 1323 RFC 2406 RFC 2488 RFC 2581 RFC 3150 RFC 3481 RFC 3649 RFC 4953 RFC 5681 RFC 5961 RFC 6349 RFC 6429 RFC 6479 RFC 6675 RFC 6928 RFC 7323 RFC 8684 RFC 9293 RFC 9467 RFC 9687 RFC 9840
- Recovery journal
A compact summary of recent stream history included in each RTP MIDI packet. After a packet loss, the receiver uses it to repair errors without asking for retransmission.
Like I'm five A cheat sheet in every package that tells the receiver what it may have missed.
- Recursive resolver
A DNS server that answers a client's question by looking up the answer on its behalf, often caching results. DoH mainly covers the link between a client and one of these.
Like I'm five A helper who goes and finds the answer for you, then remembers it.
Used in RFC 1034 RFC 1536 RFC 2308 RFC 2870 RFC 3225 RFC 3646 RFC 3655 RFC 3833 RFC 4035 RFC 4074 RFC 4339 RFC 4697 RFC 4986 RFC 5001 RFC 5222 RFC 5358 RFC 5452 RFC 5625 RFC 6106 RFC 6147 RFC 6303 RFC 6672 RFC 6731 RFC 6975 and 40 more
- RED (Random Early Detection)
A router technique that drops packets at random as a queue fills, to signal congestion early. RFC 2549 plays on the acronym: packets MAY be marked for deletion using RED paint.
Like I'm five Dropping a few things early so the line never gets too long.
Used in RFC 2309 RFC 2549 RFC 2597 RFC 2638 RFC 3150 RFC 3168 RFC 6817 RFC 7141 RFC 7567
- Redundancy Group
A set of Provider Edge devices that use ICCP to act together as a single unit for high availability.
Like I'm five A team of helpers who share notes so they can act like one helper.
- Redundant encoding
An extra, usually lower-bandwidth copy of data sent alongside later data, so that the original can be rebuilt if its own packet is lost.
Like I'm five A small backup copy of a message tucked into the next one in case the first gets lost.
- Referral
A reply that tells a client to take its query to another server that may hold the answer, instead of answering it directly.
Like I'm five When someone says, "I do not know, but try over there."
Used in RFC 1714 RFC 2167 RFC 2251 RFC 2651 RFC 7532 RFC 9499
- Reflection attack
A denial of service attack in which the attacker sends packets with the victim's address as the source to innocent nodes. Their replies then flood the victim and hide where the attack began.
Like I'm five Shouting a prank question to many people with your friend's name on it, so they all answer your friend.
- Reflexive transport address
The IP address and port that identify a client as seen by another host, typically a STUN server. When a NAT sits in between, it is the public address the NAT allocated to the client.
Like I'm five The return address on your letter as the outside world sees it.
- Refresh token
A credential used to obtain a new access token when the current one expires or is no longer valid. It is issued with the access token and is only ever sent to the authorization server.
Like I'm five A longer-lasting ticket that gets you a fresh pass when the old one runs out.
Used in RFC 6749 RFC 6819 RFC 7009 RFC 7628 RFC 7662 RFC 8252 RFC 8628 RFC 8693 RFC 8705 RFC 8898 RFC 8936 RFC 9396 RFC 9449 RFC 9560 RFC 9700 RFC 10017 RFC 10027
- Regional Internet Registry
One of the organizations, such as RIPE NCC, that receive blocks of IP address space from IANA and allocate them to providers and sites in their region.
Like I'm five A regional office that hands out big blocks of addresses to local helpers.
Used in RFC 1366 RFC 1466 RFC 1591 RFC 1879 RFC 1881 RFC 2008 RFC 2050 RFC 2517 RFC 2650 RFC 2725 RFC 2901 RFC 2928 RFC 3152 RFC 3587 RFC 3701 RFC 3707 RFC 3732 RFC 3779 RFC 3981 RFC 4012 RFC 4116 RFC 4632 RFC 4698 RFC 4773 and 29 more
- Registrar
A service provider that represents clients in registering and managing objects, such as domain names, in a registry.
Like I'm five A company that sells domain names on behalf of the actual registry.
Used in RFC 2832 RFC 3375 RFC 3915 RFC 4930 RFC 7877 RFC 8396 RFC 9154
A party that checks a subject's identity and details on behalf of a Certification Authority before a certificate is issued.
Like I'm five The person at the desk who checks your papers before the card is made.
Used in RFC 2510 RFC 4210 RFC 4211 RFC 4683 RFC 5272 RFC 7030 RFC 9483 RFC 9733 RFC 9810 RFC 10002 RFC 10004
- Registration Ownership Verifier
The ROVR is a value carried in registrations that identifies who registered an address. In this RFC it also identifies the origin of an anycast or multicast advertisement.
Like I'm five A name tag that shows who signed up for an address.
- Registration policy
The rule that controls how new assignments in a registry are accepted, such as First Come First Served, Expert Review or Standards Action. RFC 8126 defines ten well-known ones.
Like I'm five The rule for who may get a new number and what they must show first.
- Registration tree
A named group of media type subtypes, such as the standards, vendor or personal tree, that has its own naming prefix and its own approval requirements.
Like I'm five A shelf in the label library with its own rules for what may go on it.
- Registry
The authoritative database that stores all domain names and name servers for a Top Level Domain, operated by a registry operator.
Like I'm five The master list of all domain names for a particular ending (like .com or .org).
Used in RFC 2832 RFC 3375 RFC 4930 RFC 5226 RFC 7116 RFC 7500
- Rekeying
Running a new key exchange on a live connection so that fresh encryption keys replace the old ones. Limiting how much data one key protects reduces what an attacker can learn from it.
Like I'm five Swapping your secret key for a new one every so often so nobody can collect too many clues.
- Relative Distinguished Name
A single attribute and value that identifies an entry relative to its parent in the directory tree, for example
cn=John Smith.Like I'm five One piece of identifying information for a directory entry, like just the name part of a full address.
- Relative distinguished name
One component of a distinguished name. It is made of one or more attribute type and value pairs that identify an entry among its siblings.
Like I'm five One piece of an address, like just the street name or just the city.
- RELAX NG
An XML schema language that describes the allowed structure and contents of XML documents. It is Part 2 of the ISO/IEC DSDL family of standards.
Like I'm five A set of building-block rules for what a document is allowed to look like.
- Relay agent (BOOTP forwarder)
A gateway or other host on the client's network that forwards broadcast BOOTP requests to a server on another network. It writes its own address into the giaddr field so the reply can find its way back.
Like I'm five A messenger who carries your question to another building and brings the answer back.
Used in RFC 951 RFC 1532 RFC 1541 RFC 1542 RFC 2131 RFC 3011 RFC 3046 RFC 3074 RFC 3118 RFC 3256 RFC 3315 RFC 3456 RFC 3527 RFC 3588 RFC 3993 RFC 4014 RFC 4030 RFC 4039 RFC 4243 RFC 4388 RFC 4580 RFC 4649 RFC 4994 RFC 5007 and 47 more
- Relay-MTA
An X.400 Message Transfer Agent that serves as a routing point between MHS domains, often supporting multiple network protocol stacks to bridge domains that use different technologies.
Like I'm five A relay server that carries mail between different email systems.
- RELOAD
REsource LOcation And Discovery, a peer-to-peer signaling protocol used to maintain an overlay network and to store data in and retrieve data from the overlay.
Like I'm five A way for a group of computers to team up and share a common storage space without a boss computer.
- Relying Party
A system that accepts identity information from an identity provider in order to sign a user in.
Like I'm five The website that trusts someone else's word about who you are.
Used in RFC 4683 RFC 6024 RFC 6487 RFC 6489 RFC 6595 RFC 7833 RFC 8176 RFC 8182 RFC 8416 RFC 8473 RFC 8630 RFC 8897 RFC 9286 RFC 9399 RFC 9455 RFC 9560 RFC 9589 RFC 9691 RFC 9829
- Remote Attestation
A procedure in which one system produces believable information about its own state so a remote party can decide whether to trust it. In RATS the information is called Evidence.
Like I'm five Showing proof to someone far away that you have not been tampered with.
- Remote attestation
A process in which a device, the attester, produces signed evidence about its own state so that another party can decide whether to trust it.
Like I'm five A device showing a signed report card about itself so others can decide to trust it.
- Remote Job Entry
A network service that lets users submit batch computing jobs to a distant computer and retrieve results, commonly abbreviated RJE.
Like I'm five Sending a computing job to a faraway computer to run it there.
- Remote Procedure Call
A protocol that lets a program call a function or routine that runs on another computer over the network, as if it were a local function call.
Like I'm five A way to ask another computer to run a piece of code for you.
Used in RFC 1045 RFC 1050 RFC 1057 RFC 1094 RFC 1813 RFC 2188 RFC 5531 RFC 8166 RFC 8167
- Rendezvous point
A well-known place where hosts behind a NAT or firewall register an address and port, so that peers can contact them.
Like I'm five A meeting spot where hidden people leave a note saying how to reach them.
Used in RFC 2117 RFC 2201 RFC 2362 RFC 2934 RFC 3446 RFC 3618 RFC 3956 RFC 4601 RFC 4608 RFC 4609 RFC 4610 RFC 5015 RFC 5059 RFC 5110 RFC 5207 RFC 5240 RFC 6226 RFC 6513 RFC 7438 RFC 7442 RFC 7582 RFC 7761 RFC 8487 RFC 8775 and 5 more
- Rendezvous Server
A server that relays incoming connection requests to a mobile host at its current location, maintaining reachability while the host's IP address changes.
Like I'm five A relay station that forwards messages to a computer that keeps moving, so you don't need to know where it is.
- Renumbering
Changing the IP addresses of hosts and networks. RFC 1918 notes that moving a host between private and public use, or merging two private internets, can require it, along with DNS and configuration changes.
Like I'm five Giving every house on a street a new house number.
Used in RFC 1627 RFC 1787 RFC 1900 RFC 1918 RFC 2008 RFC 2050 RFC 2071 RFC 2072 RFC 2101 RFC 2260 RFC 2462 RFC 2874 RFC 2894 RFC 3177 RFC 3178 RFC 3194 RFC 3364 RFC 4085 RFC 4116 RFC 4193 RFC 4242 RFC 4984 RFC 5220 RFC 5375 and 13 more
- Rep-encapsulation
The process of replicating a packet to multiple destinations and encapsulating each copy into a separate tunnel.
Like I'm five Making copies of a package and sending each copy down a different tube.
- Repair Flow
A media flow consisting of repair packets generated by FEC encoding that can be used to recover missing or corrupted source packets.
Like I'm five Extra packets sent alongside the main video that can be used to fix packets that arrived broken or not at all.
- Repair window
The time spanned by a FEC block, covering its source packets and the matching repair packets. A receiver waits at least this long before declaring a decoding failure.
Like I'm five How long you wait for late pieces before giving up.
- Replay attack
An attack in which a recorded message is sent again to make the receiver act on it twice. 0-RTT data in TLS is exposed to this.
Like I'm five Copying someone's note and handing it over again.
Used in RFC 1057 RFC 1135 RFC 1334 RFC 1704 RFC 1760 RFC 1938 RFC 1994 RFC 2025 RFC 2085 RFC 2136 RFC 2203 RFC 2243 RFC 2274 RFC 2289 RFC 2419 RFC 2420 RFC 2444 RFC 2571 RFC 2574 RFC 2617 RFC 2712 RFC 2747 RFC 2750 RFC 2769 and 194 more
- Replay cache
A server's record of recently seen authenticators, used to reject a copy of an earlier request that an attacker captured and resent within the clock-skew window.
Like I'm five A list of notes already seen today, so a copied note gets turned away.
- Replay protection
A defense against an attacker who records valid packets and sends them again later. SRTP rejects packets whose index has already been seen.
Like I'm five Throwing away a note you have already read.
Used in RFC 1460 RFC 1507 RFC 1725 RFC 1910 RFC 1961 RFC 1964 RFC 2002 RFC 2006 RFC 2082 RFC 2085 RFC 2195 RFC 2203 RFC 2274 RFC 2401 RFC 2402 RFC 2406 RFC 2574 RFC 2743 RFC 2744 RFC 2748 RFC 2779 RFC 2894 RFC 3012 RFC 3185 and 124 more
- Replication segment
A Segment Routing segment that tells a node to copy an incoming packet and send the copies to a set of downstream nodes. Chains of them can form a multicast-style tree.
Like I'm five A signpost that says: make copies here and send one down each road.
- Repository Object Identifier
The ROID, an identifier assigned to an object in the registry when it was created. Domain and host records in a deposit carry their ROID.
Like I'm five A unique ID number given to each record when it is first made.
- Representation
Information that reflects the state of a resource, together with metadata such as its media type, in a form that can be sent in an HTTP message. One resource can have several representations, for example HTML and JSON.
Like I'm five The package the thing is shipped in. The same thing can come in different packages.
Used in RFC 1003 RFC 1014 RFC 4506 RFC 7231 RFC 8132 RFC 8144 RFC 9110 RFC 9530
- Reputon
A single independent JSON object holding reputation information about one subject. A reputation query returns one or more of them.
Like I'm five A little report card that says who is being rated, who is rating them and what score they got.
- Request for Comments
A document published by the IETF describing Internet standards, technologies, and procedures.
Like I'm five An official document that describes how the Internet works.
- Request Object
A JSON Web Token that carries the parameters of an OAuth authorization request as claims. It can be signed and optionally encrypted.
Like I'm five Your order written on a card that you sign so nobody can change it.
- Request smuggling
An attack that exploits two HTTP recipients, such as a proxy and a server, disagreeing about where a request ends, so a hidden second request slips past checks.
Like I'm five Hiding a second note inside the first so one person sees one note and another sees two.
- Request target
The part of an HTTP request line, after the method, that says what the request is for. It takes one of four forms: origin, absolute, authority or asterisk.
Like I'm five The address you write on the front of the envelope.
- Request-Line
The first line of an HTTP/1.0 full request: a method, the Request-URI and the HTTP version, separated by spaces and ended by CRLF, for example
GET /index.html HTTP/1.0.Like I'm five The first line of the note that says what you want and where.
- Request-Routing
The activity of directing a content request from a user agent to a suitable surrogate, typically based on network conditions, load, and geographic proximity.
Like I'm five The decision of which surrogate should handle your request, made by looking at where you are and how busy each surrogate is.
- Requirement key word
One of the capitalized words RFC 2119 defines to state how strongly a rule applies: MUST, MUST NOT, SHOULD, SHOULD NOT and MAY, with synonyms such as REQUIRED, SHALL, RECOMMENDED and OPTIONAL.
Like I'm five A shouting word that tells you how strict a rule is.
Used in RFC 1100 RFC 1140 RFC 1540 RFC 2119 RFC 2193 RFC 2223 RFC 2251 RFC 2281 RFC 2306 RFC 2356 RFC 2360 RFC 2379 RFC 2394 RFC 2505 RFC 2566 RFC 2609 RFC 2681 RFC 2750 RFC 2784 RFC 2846 RFC 2857 RFC 2911 RFC 2984 RFC 2989 and 157 more
- Requirement level
The specification of how important it is for a system to implement a protocol, categorized as required, recommended, elective, limited use, or not recommended.
Like I'm five How much you need to follow a rule: must do it, should do it, can do it, or do not do it.
- Research Group (RG)
A group in the IRTF that explores long-term research questions and ideas, with no requirement to produce standards or reach consensus.
Like I'm five A group of researchers studying big questions about how the Internet could work better.
- Resolver
A DNS client or server component that looks up names on behalf of programs; stub resolvers ask recursive resolvers, which ask authoritative servers.
Like I'm five The helper who looks things up in the phone book for you.
Used in RFC 881 RFC 882 RFC 883 RFC 921 RFC 974 RFC 1031 RFC 1032 RFC 1033 RFC 1034 RFC 1118 RFC 1178 RFC 1535 RFC 1536 RFC 1612 RFC 1737 RFC 2168 RFC 2182 RFC 2276 RFC 2535 RFC 2672 RFC 2826 RFC 3008 RFC 3044 RFC 3187 and 47 more
- Resource
In HTTP, the target of a request: anything that can be identified by a URI, such as a document, an image, a collection or a service. A resource is distinct from the representations that are sent for it.
Like I'm five The thing you want, like a photo, before it gets packed into a box to be sent.
Used in RFC 268 RFC 274 RFC 276 RFC 286 RFC 518 RFC 1152 RFC 2413 RFC 3334 RFC 3532 RFC 4195 RFC 4198 RFC 4463 RFC 5023 RFC 5279 RFC 5362 RFC 5689 RFC 6288 RFC 6289 RFC 6903 RFC 7396 RFC 7643 RFC 7853 RFC 8720 RFC 9110 and 1 more
- Resource binding
The final step of client stream negotiation in which the client is given a resourcepart, producing a full JID that identifies this particular connection of the account.
Like I'm five Telling the front desk which room you are in so mail finds you.
- Resource list server
A SIP server that subscribes to a set of resources on behalf of a client and reports changes in their state through a single subscription dialog.
Like I'm five A helper who watches a whole list of things for you and tells you when anything changes.
- Resource owner
In OAuth, an entity able to grant access to a protected resource. When it is a person, it is called the end-user.
Like I'm five The person whose stuff it is, who decides who can use it.
Used in RFC 2819 RFC 5849 RFC 6749 RFC 7009 RFC 7635 RFC 7662 RFC 9068 RFC 9200 RFC 9396 RFC 9635 RFC 9700 RFC 9767
- Resource Public Key Infrastructure
A system for authenticating Internet number resource information using digital certificates, used primarily to secure routing information.
Like I'm five A way to prove you own your Internet addresses or route numbers using digital certificates.
Used in RFC 6480 RFC 6481 RFC 6482 RFC 6487 RFC 6492 RFC 6493 RFC 6810 RFC 6811 RFC 6945 RFC 7115 RFC 7132 RFC 8182 RFC 8205 RFC 8207 RFC 8209 RFC 8210 RFC 8360 RFC 8416 RFC 8488 RFC 8635 RFC 9255 RFC 9319 RFC 9455 RFC 9582 and 4 more
- Resource record
The basic unit of DNS data. Each record has a name, type, class, time to live, and type-specific data (RDATA).
Like I'm five One index card with a name on it and a fact about that name.
Used in RFC 882 RFC 883 RFC 974 RFC 1033 RFC 1035 RFC 1183 RFC 1279 RFC 1348 RFC 1480 RFC 1530 RFC 1664 RFC 1703 RFC 1706 RFC 1712 RFC 1876 RFC 1886 RFC 1912 RFC 1995 RFC 1996 RFC 2065 RFC 2136 RFC 2163 RFC 2168 RFC 2181 and 98 more
- Resource server
The server that holds the protected data or functions in OAuth. It checks the access token on each request and answers or refuses.
Like I'm five The guard at the door who checks your pass.
Used in RFC 6749 RFC 6750 RFC 6819 RFC 7635 RFC 7662 RFC 8705 RFC 8707 RFC 9068 RFC 9200 RFC 9201 RFC 9203 RFC 9396 RFC 9430 RFC 9431 RFC 9449 RFC 9470 RFC 9594 RFC 9635 RFC 9700 RFC 9701 RFC 9728 RFC 9767 RFC 9770 RFC 10017
- Resource transponder
A system that combines metadata attached to a resource with an agent program that automatically notifies resource location systems when the resource moves or changes.
Like I'm five A name tag and robot that keep directories up to date about where a resource lives.
- Response set
A defined group of assertions and extra metadata that a reputation service provider can include in a reply for a given reputation application.
Like I'm five The list of things a reputation helper is allowed to say about something.
- Response splitting
An attack, also called CRLF injection, in which an attacker gets carriage-return and line-feed characters into a response header so that one response looks like two.
Like I'm five Sneaking a fake "end of letter" into a letter so the rest looks like a new letter.
Used in RFC 9112
- REST
Representational State Transfer, an architectural style where resources have web addresses and servers keep no client session state. Clients move between states by following links.
Like I'm five A way of building websites where every thing has its own address and you follow links to get around.
- RESTCONF
A REST-based variant of NETCONF that uses HTTP methods and is lighter-weight than NETCONF, defined in RFC 8040.
Like I'm five A web-friendly version of NETCONF for configuring network devices.
Used in RFC 8071 RFC 8072 RFC 8242 RFC 8341 RFC 8407 RFC 8650 RFC 8783 RFC 9243 RFC 9731 RFC 9907
- Retargeting
Changing the intended destination of a call or request while it is being routed, for example when a call is forwarded to another number.
Like I'm five Sending a letter on to a different address than the one on the envelope.
- Retransmission
Sending a segment again because no acknowledgment for it came back before a timer expired. TCP keeps a copy on a retransmission queue until the data is acknowledged.
Like I'm five If your friend does not say they got the letter, you send another copy.
Used in RFC 65 RFC 68 RFC 71 RFC 442 RFC 516 RFC 635 RFC 675 RFC 700 RFC 793 RFC 889 RFC 896 RFC 905 RFC 907 RFC 908 RFC 916 RFC 938 RFC 964 RFC 998 RFC 1002 RFC 1008 RFC 1016 RFC 1045 RFC 1094 RFC 1323 and 119 more
- Retransmission Timeout (RTO)
The time interval a sender waits without receiving an acknowledgment before assuming the data was lost and resending it.
Like I'm five The deadline the sender sets before deciding a message was lost and sending it again.
- Retry-After
An HTTP header that tells a client how long to wait before trying again, as a number of seconds or as a date. RFC 6585 allows it on 429 responses.
Like I'm five A sign saying, 'come back in an hour'.
Used in RFC 5390 RFC 6585 RFC 7339 RFC 7480 RFC 7481 RFC 8030 RFC 9457
- Return routability
A check that a node can actually receive packets sent to a claimed address, by sending it a secret token and requiring that the token be used in the reply.
Like I'm five Sending a secret code to an address and seeing if the right person uses it.
- Return routability check
A test in which a receiver sends a challenge to a claimed address and accepts the address only if the reply proves the peer can be reached there.
Like I'm five Sending a letter to a new address and waiting for a reply to prove someone really lives there.
- Reverse DNS
A DNS lookup that finds the hostname associated with an IP address, performed by querying IN-ADDR.ARPA zones with the address octets reversed.
Like I'm five Asking "who owns this IP address?" instead of "what is the IP address of this website?"
Used in RFC 2317 RFC 4472 RFC 5158 RFC 6305 RFC 7793 RFC 8686 RFC 8777
- Reverse lookup
A DNS query that starts from an address and looks for the host name. For IPv6 it uses a name built under the IP6.ARPA domain.
Like I'm five Looking up a name when all you have is the number.
- Reverse Path Forwarding check
A check that accepts a multi-destination packet only if it arrives on the port where it is expected to arrive. Packets on any other port are dropped.
Like I'm five A guard who only lets a visitor in through the door the visitor was supposed to use.
Used in RFC 922 RFC 1716 RFC 3704 RFC 3973 RFC 5015 RFC 5132 RFC 5496 RFC 5635 RFC 6831 RFC 7761 RFC 7891 RFC 8243 RFC 8361 RFC 8487 RFC 9466 RFC 9856
- Reverse tunnel
In Mobile IP, a tunnel that starts at the mobile node's care-of address and ends at the home agent, carrying the node's outgoing packets back toward its home network.
Like I'm five A path that sends your outgoing mail back home first, so it can be sent onward from there.
- RFC Editor
The function that edits and publishes documents in the RFC series.
Like I'm five The librarian who prepares and publishes each finished document.
Used in RFC 72 RFC 825 RFC 1111 RFC 1160 RFC 1199 RFC 1280 RFC 1311 RFC 1358 RFC 1500 RFC 1543 RFC 1594 RFC 1600 RFC 1602 RFC 1603 RFC 1720 RFC 1899 RFC 2014 RFC 2026 RFC 2028 RFC 2223 RFC 2399 RFC 2418 RFC 2441 RFC 2468 and 60 more
- RFNM
Ready For Next Message, the reply an ARPANET destination IMP sends to say a message arrived and the source may send another.
Like I'm five A short note back saying got it, you can send the next one.
- RMON
Remote Network Monitoring: a standard framework for network management agents to observe and report on traffic characteristics on network links.
Like I'm five Tools that watch the network and tell you what they see.
- RMON probe
A remote monitoring agent, implemented as independent software or hardware, that watches traffic on a network and collects statistics for a management station to read.
Like I'm five A little watcher on the network that counts what goes by and reports it when asked.
- ROADM
A Reconfigurable Optical Add/Drop Multiplexer, an optical node that can be reconfigured to add or drop wavelengths. A node that cannot be reconfigured is called a FOADM.
Like I'm five A railway switch for light colors that can be set to send each color down a different track.
- Roaming
The ability of a mobile device to move between different access points or networks while maintaining connectivity and authentication state.
Like I'm five Moving between different Wi-Fi networks without losing your connection.
- Robust Header Compression (ROHC)
A framework, with profiles for specific header sets, for shrinking packet headers on a link and restoring them at the other end.
Like I'm five A trick for writing the long label on every parcel in a much shorter way.
- Robust XML Encoding Rules (RXER)
Encoding rules that convert ASN.1 values into XML documents, making ASN.1-defined data human-readable and compatible with standard XML tools.
Like I'm five Instructions for turning computer data shorthand into readable XML tags.
- Robustness principle
Be liberal in what you accept and conservative in what you send. Software should tolerate unexpected input and unknown values from other hosts, while its own output sticks to the plain, well-defined forms of the protocol.
Like I'm five Listen kindly, speak carefully.
Used in RFC 1122 RFC 1123 RFC 1812 RFC 1958 RFC 2145 RFC 2360 RFC 3360 RFC 5198 RFC 7493 RFC 8504 RFC 9413
- ROHC
RObust Header Compression, a framework for compressing packet headers using profiles that each describe how to compress a certain protocol stack.
Like I'm five A way of making the labels on packets much smaller so they use less space on the wire.
- Role-Based Access Control
An access control scheme in which decisions are based on the role or group membership of the requester rather than their identity alone.
Like I'm five Letting someone in because of their job title rather than their name.
- Rollover counter (ROC)
A 32-bit counter in SRTP that records how many times the 16-bit RTP sequence number has wrapped. It is never sent in packets.
Like I'm five Counts how many times the packet counter has gone back to zero.
Used in RFC 3711 RFC 4383 RFC 4771 RFC 5669 RFC 7714 RFC 8870
- Root DSE
The special entry at the top of an LDAP server that describes the server itself. Servers list the controls they support there, in the supportedControl attribute.
Like I'm five The front page of a server's own notebook that says what it can do.
Used in RFC 2829 RFC 3045 RFC 3674 RFC 4512 RFC 4521 RFC 4527 RFC 4528
- Root key
A child key derived from the EMSK, such as a USRK, DSRK or DSUSRK. It is used to derive further keys for protecting a specific service.
Like I'm five A smaller key made from the master key, used to make even more keys for one job.
- Roster
In XMPP, a user's contact list, stored by the server. Each roster item identifies a contact by JID and tracks the subscription state and any groups or nicknames.
Like I'm five Your friends list in a chat app.
- Rough consensus
The IETF's way of reaching decisions without voting. A large part of the community must agree, and anyone who disagrees must convince others or be overruled.
Like I'm five Everyone talks it through until nearly everybody agrees, instead of counting hands.
Used in RFC 2418 RFC 3844 RFC 3929 RFC 3935 RFC 7241 RFC 7282
- Round-Trip Delay
The time between sending a packet to a node and receiving its reply back at the sender. It includes propagation, queuing and the processing time at the replying node.
Like I'm five How long it takes to shout across a valley and hear the echo.
- Round-trip time
The time for a message to travel to another node and for the reply to come back. It is often abbreviated RTT.
Like I'm five How long it takes to shout across a field and hear the echo.
Used in RFC 2140 RFC 2861 RFC 3390 RFC 5348 RFC 5357 RFC 6298 RFC 7323 RFC 7560 RFC 7918 RFC 7982 RFC 8289 RFC 8337 RFC 8912 RFC 9406 RFC 9438 RFC 9616 RFC 9959
- Route aggregation
Replacing many specific routes with one shorter-prefix route that covers them, so that routers elsewhere need fewer table entries.
Like I'm five Putting a whole street under one sign.
Used in RFC 1125 RFC 1322 RFC 1338 RFC 1380 RFC 1466 RFC 1467 RFC 1481 RFC 1518 RFC 1519 RFC 1520 RFC 1629 RFC 1655 RFC 1752 RFC 1771 RFC 1772 RFC 1773 RFC 1774 RFC 1787 RFC 1887 RFC 1888 RFC 1900 RFC 1930 RFC 1997 RFC 2008 and 54 more
- Route Distinguisher
An 8-octet value prepended to a route so that the same address used by different VPNs stays unique inside BGP.
Like I'm five A label that keeps two houses with the same street number apart.
Used in RFC 2547 RFC 4364 RFC 4365 RFC 4381 RFC 4659 RFC 6368 RFC 6512 RFC 6514 RFC 6882 RFC 7246 RFC 7611 RFC 8299 RFC 9181
- Route flap damping
A BGP mechanism that gives a route a penalty each time it changes and temporarily suppresses the route once the penalty passes a threshold. It is meant to reduce routing churn.
Like I'm five A rule that gives a time-out to a network path that keeps switching on and off.
- Route leak
The case where AS-A advertises routes it received from AS-B to its own neighbors, although AS-A is not a transit provider for the prefixes in those routes.
Like I'm five Passing along directions to people you were never supposed to share them with.
- Route Optimization
A Mobile IPv6 feature that lets packets flow directly between the mobile node and a correspondent node, bypassing the home agent for faster communication.
Like I'm five A shortcut so packets do not have to go through the home office.
- Route Origin Authorization
A digitally signed RPKI object in which an address block holder authorizes one Autonomous System to originate routes to listed prefixes. It is usually shortened to ROA.
Like I'm five A signed permission slip saying which network may announce certain addresses.
A signed object (ROA) with which a prefix holder names the ASes that are authorized to originate routes for that prefix.
Like I'm five A signed note saying which networks are allowed to announce a given address block.
Used in RFC 6482 RFC 6483 RFC 6491 RFC 6811 RFC 6907 RFC 7115 RFC 7132 RFC 7454 RFC 8205 RFC 8210 RFC 8360 RFC 8416 RFC 9319 RFC 9455 RFC 9774
- Route Reflector
A BGP speaker configured to advertise IBGP-learned routes to other internal BGP peers, normally forbidden in standard IBGP to prevent loops.
Like I'm five A router that has permission to pass along internal network information to other routers.
Used in RFC 1966 RFC 2796 RFC 3345 RFC 4456 RFC 6198 RFC 6368 RFC 7524 RFC 7611 RFC 7705 RFC 9107 RFC 9541 RFC 9815
- Route Server
A BGP speaker at an Internet exchange that passes routes between peers and, by design, does not insert its own AS number into the AS_PATH.
Like I'm five A shared helper at a meeting place that passes messages between networks without signing them.
- Route tag
A 16-bit field in a RIP-2 entry that must be kept and readvertised with the route, used for example to tell internal routes from ones imported from another protocol.
Like I'm five A sticker on a route saying where it came from.
Used in RFC 1721 RFC 1723 RFC 1724 RFC 1745 RFC 2080 RFC 2081 RFC 2453 RFC 3101 RFC 4577 RFC 5130 RFC 7777 RFC 9067 RFC 9398 RFC 9403 RFC 9513
- Route Target
A label attached to a BGP route in a VPN that controls which VPN routing tables import the route.
Like I'm five A colored sticker on a route that tells each receiver whether to keep it.
Used in RFC 4360 RFC 4364 RFC 4365 RFC 4382 RFC 4577 RFC 4684 RFC 4761 RFC 6074 RFC 6368 RFC 6514 RFC 6624 RFC 7024 RFC 7257 RFC 7432 RFC 7543 RFC 7611 RFC 7734 RFC 7900 RFC 8049 RFC 8299 RFC 8365 RFC 8466 RFC 9135 RFC 9181 and 1 more
- Router
A device that forwards packets between networks based on their IP destination. It does not forward link-layer broadcasts, which is why RARP stays on one segment.
Like I'm five A post office between neighbourhoods that only passes along mail that has an address.
Used in RFC 321 RFC 331 RFC 334 RFC 335 RFC 395 RFC 791 RFC 950 RFC 951 RFC 994 RFC 1009 RFC 1015 RFC 1017 RFC 1054 RFC 1104 RFC 1112 RFC 1142 RFC 1177 RFC 1191 RFC 1195 RFC 1208 RFC 1242 RFC 1256 RFC 1269 RFC 1272 and 272 more
- Router Advertisement
A message IPv6 routers send to announce their presence together with various link and Internet parameters. Hosts use it to configure themselves.
Like I'm five A router shouting hello and telling everyone how the network works.
Used in RFC 4135 RFC 4191 RFC 6104 RFC 6105 RFC 6775 RFC 7157 RFC 7772 RFC 8043 RFC 8106 RFC 8319 RFC 8781 RFC 8801
- Router Alert Option
An option in the IP header that tells routers along the path to examine the packet more closely instead of just forwarding it.
Like I'm five A sticker on a package that tells every helper along the way to open it and look inside.
- Router ID
A 32-bit number that uniquely identifies an OSPF router within the autonomous system.
Like I'm five The router's name tag.
Used in RFC 1131 RFC 1252 RFC 1253 RFC 1403 RFC 1745 RFC 1771 RFC 1793 RFC 2072 RFC 2178 RFC 2328 RFC 2370 RFC 2740 RFC 3101 RFC 3446 RFC 3480 RFC 3623 RFC 3630 RFC 3684 RFC 3784 RFC 4273 RFC 4444 RFC 4561 RFC 4652 RFC 4750 and 55 more
- Router Solicitation
An ICMPv6 message sent by a host to request router advertisement and network configuration information from the local network.
Like I'm five A host asking the network: 'Hello, what are my IP settings here?'
- Routing
The process of determining a path through a network and forwarding data packets along that path toward their destination.
Like I'm five Figuring out which way to send a message so it reaches the right place.
- Routing and Wavelength Assignment
The constrained path computation that picks both a route and a wavelength for an optical connection. It is usually shortened to RWA.
Like I'm five Choosing the road and the color of light for a trip.
- Routing Area
In ASON, a partition of the network used for routing, identified in the control plane by an RA ID. Routing areas can contain smaller routing areas, which gives a hierarchy.
Like I'm five One region of a big map, which can hold smaller regions inside it.
- Routing Domain
A set of routers and hosts that use the same routing protocol and routing procedures, wholly contained within a single Administrative Domain.
Like I'm five A group of routers using the same routing rules within one organization.
Used in RFC 1069 RFC 1136 RFC 1237 RFC 1388 RFC 1518 RFC 1629 RFC 1887
- Routing Information Base
A data structure containing a list of routes, along with administrative data, that a router uses to forward packets.
Like I'm five A table of all the routes a router knows about.
Used in RFC 4098 RFC 6396 RFC 8022 RFC 8349 RFC 8430 RFC 8431 RFC 8671 RFC 9069
- Routing Information Base (RIB)
The table of routes that a router holds and chooses from when deciding where to send traffic. Selected routes are then installed for forwarding.
Like I'm five The router's list of directions it picks from.
- Routing Locator
A LISP address that says where in the network an endpoint can currently be reached, usually the address of a tunnel router.
Like I'm five The street address where mail for you is currently delivered.
- Routing Locator (RLOC)
In LISP, a topological address used for routing and forwarding through the Internet, bound to the host's current location.
Like I'm five The address of where your computer is right now on the Internet.
Used in RFC 5558 RFC 6139 RFC 6830 RFC 6831 RFC 6832 RFC 6833 RFC 6835 RFC 6836 RFC 6837 RFC 7834 RFC 7835 RFC 7954 RFC 8060 RFC 8111 RFC 9299 RFC 9300 RFC 9301 RFC 9735 RFC 9962
- Routing policy
The rules a network uses to decide which routes it accepts from neighbors, which it announces to them, and which it prefers.
Like I'm five The rules a town uses to decide which roads visitors may use and which roads it tells others about.
- Routing registry
A repository of routing policy information, such as which networks and autonomous systems exist and who may announce which prefixes. The Internet Routing Registry is a set of such repositories.
Like I'm five A shared book that lists who owns which parts of the Internet map.
- RowStatus
A textual convention used for the status column of a conceptual table row. It lets a management station create, activate, suspend and delete rows with ordinary set operations.
Like I'm five A switch on each table row that says whether the row is being set up, ready, or being thrown away.
- RPCSEC_GSS
A security flavor for ONC RPC that uses GSS-API mechanisms such as Kerberos to authenticate users to servers. NFSv4.1 clients and servers must implement it.
Like I'm five A way for a computer to prove who a person is using a trusted ID system like Kerberos.
- RPKI manifest
A signed file that lists every signed object at an RPKI repository publication point, with a file name and hash for each. It lets a relying party detect missing, stale or altered files.
Like I'm five A packing slip that lists everything that should be in the box.
- RPL
The IPv6 Routing Protocol for Low-Power and Lossy Networks, a distance vector protocol that organizes devices into a root-based DODAG.
Like I'm five A way for tiny, weak-battery devices to figure out how to pass messages along.
Used in RFC 6551 RFC 6552 RFC 6719 RFC 8036 RFC 8138 RFC 9009 RFC 9010 RFC 9035 RFC 9685 RFC 9854 RFC 9866 RFC 9914
- RPSL
The Routing Policy Specification Language, a text format in which routing registry objects are written as lines of attribute names and values.
Like I'm five A fill-in-the-blanks form language for describing network ownership and rules.
- RRset
A set of DNS resource records with the same owner name, class and type. DNSSEC signatures cover whole RRsets, not single records.
Like I'm five A group of matching entries signed together as one.
Used in RFC 2136 RFC 2181 RFC 2308 RFC 2535 RFC 3007 RFC 3008 RFC 3226 RFC 4033 RFC 4034 RFC 4035 RFC 4501 RFC 4509 RFC 4592 RFC 4697 RFC 4956 RFC 5011 RFC 5074 RFC 5483 RFC 5507 RFC 5910 RFC 6698 RFC 7344 RFC 7583 RFC 7671 and 16 more
- RRSIG
Resource Record Signature. The DNSSEC record that holds a digital signature over an RRset, with inception and expiration times that bound its validity.
Like I'm five The wax seal itself, with a date it stops being good.
Used in RFC 3755 RFC 4033 RFC 4034 RFC 4035 RFC 4398 RFC 4470 RFC 4509 RFC 4956 RFC 5011 RFC 5702 RFC 5910 RFC 5933 RFC 6605 RFC 6840 RFC 6841 RFC 6975 RFC 7129 RFC 7583 RFC 7646 RFC 8005 RFC 8080 RFC 8749 RFC 8976 RFC 9364 and 3 more
- RRULE
The recurrence rule property, whose value is a list of NAME=VALUE parts such as FREQ=WEEKLY;BYDAY=TU that describe a repeating event.
Like I'm five One short rule that says "every Tuesday" instead of listing each Tuesday.
Used in RFC 2445 RFC 5545 RFC 7265 RFC 7529 RFC 7953 RFC 8984
- RSA
A public key cryptosystem whose key consists of two numbers, commonly written e and n. It can be used to create and verify digital signatures.
Like I'm five A lock-and-key system where anyone can check your stamp but only you can make it.
- RSVP
The Resource ReSerVation Protocol, which sets up reservations of network resources for a flow using Path and Resv messages.
Like I'm five A way to ask the network to save space for your traffic, like booking a table.
Used in RFC 2207 RFC 2208 RFC 2212 RFC 2380 RFC 2381 RFC 2490 RFC 2502 RFC 2745 RFC 2746 RFC 2747 RFC 2749 RFC 2814 RFC 2872 RFC 2961 RFC 2996 RFC 2997 RFC 3006 RFC 3033 RFC 3175 RFC 3209 RFC 3520 RFC 3936 RFC 4495 RFC 4804 and 7 more
- RSVP-TE
RSVP extensions for Traffic Engineering, allowing explicit path setup and management of label switched paths in MPLS networks.
Like I'm five A way to control exactly which path data takes through a network.
Used in RFC 3468 RFC 3473 RFC 3496 RFC 4208 RFC 4783 RFC 4873 RFC 4875 RFC 4920 RFC 4974 RFC 5420 RFC 7260 RFC 7898 RFC 8131 RFC 8149 RFC 8359 RFC 8370 RFC 8577 RFC 8625 RFC 9059
- rsync
A file synchronization tool that copies files between machines and, by default, skips any file whose last modification time and size already match on both sides.
Like I'm five A copying tool that skips files that look the same on both computers.
- RTCP
The RTP Control Protocol. It carries reports about delivery quality and session membership alongside an RTP stream.
Like I'm five The status messages that ride along with a call.
Used in RFC 1889 RFC 1890 RFC 2326 RFC 2354 RFC 2508 RFC 2862 RFC 2959 RFC 3158 RFC 3264 RFC 3497 RFC 3550 RFC 3551 RFC 3556 RFC 3605 RFC 3611 RFC 3711 RFC 3714 RFC 3890 RFC 4175 RFC 4352 RFC 4570 RFC 4571 RFC 4585 RFC 4586 and 120 more
- RTP
The Real-time Transport Protocol. It carries audio and video over IP with sequence numbers and timestamps so the receiver can play them back in order.
Like I'm five The delivery truck for live sound and pictures.
Used in RFC 741 RFC 1889 RFC 1890 RFC 2029 RFC 2032 RFC 2035 RFC 2038 RFC 2190 RFC 2198 RFC 2250 RFC 2326 RFC 2327 RFC 2343 RFC 2354 RFC 2429 RFC 2431 RFC 2435 RFC 2448 RFC 2507 RFC 2508 RFC 2658 RFC 2689 RFC 2705 RFC 2733 and 371 more
- RTP header extension
Extra data placed in the header of an RTP packet using a general extension mechanism. It lets a sender attach small pieces of metadata to individual packets.
Like I'm five A small sticker added to a packet to carry extra information.
- RTP mixer
An intermediate system that combines RTP streams from several sources into one new stream and becomes the synchronization source of the result.
Like I'm five A person who blends several voices into one and sends it on.
Used in RFC 1889 RFC 2508 RFC 3550 RFC 4245 RFC 4353 RFC 4575 RFC 5104 RFC 5239 RFC 5686 RFC 5760 RFC 6341 RFC 6464 RFC 6465 RFC 6642 RFC 6679 RFC 6792 RFC 7201 RFC 7656 RFC 7667 RFC 7728 RFC 7866 RFC 8108 RFC 8286 RFC 8834 and 4 more
- RTP translator
An intermediate system that forwards RTP packets while keeping the original SSRC identifiers, for example converting encodings or bridging networks.
Like I'm five A relay who passes your message along without changing who said it.
Used in RFC 1889 RFC 3550 RFC 5104 RFC 5686 RFC 5760 RFC 5762 RFC 6642 RFC 6679 RFC 6792 RFC 7022 RFC 7201 RFC 7656 RFC 7667 RFC 7728 RFC 7866 RFC 8079 RFC 8286 RFC 8861
- RTSP
The Real-Time Streaming Protocol, used to set up and control one or more media streams that deliver media to receivers.
Like I'm five The remote control that tells a media server what to play.
- Rule set
An unordered collection of authorization rules that together form a policy. Each rule pairs conditions with the permissions it grants when those conditions are all true.
Like I'm five A pile of 'if this, then you may see that' cards.
- Run-length encoding
A compact way to describe a sequence by recording how long each run of identical values lasts instead of listing every value.
Like I'm five Instead of writing 'lost, lost, lost, lost', you write 'lost four times'.