RARP - Reverse Address Resolution Protocol

What is RARP?

RARP stands for Reverse Address Resolution Protocol. It is a network protocol used by a device to discover its own IP address when it only knows its MAC (hardware) address. It’s essentially the reverse of ARP.

Why is RARP useful?

  • RARP was useful in early networked systems where: * Devices (like diskless workstations) did not have permanent storage to save their IP address. * They needed to request their IP address from a RARP server at boot time. * It allowed automatic IP assignment based on the device’s MAC address.

  • RARP is now largely obsolete and has been replaced by more flexible protocols like BOOTP and DHCP.

How it works?

  • Device boots up – It knows its MAC address but not its IP address.

  • Sends RARP request – A broadcast message is sent asking, “What is my IP address?”.

  • RARP server responds – The server looks up the MAC address in a table and replies with the corresponding IP address.

  • Device configures itself – It uses the received IP address to join the network.

Where is RARP used?

  • Diskless workstations – Early computers that booted over the network.

  • Embedded systems – Devices that needed to get an IP address without user configuration.

  • Legacy networks – Before DHCP became the standard.

Which OSI layer does this protocol belong to?

  • It uses MAC addresses to identify devices.

  • It works below the IP layer, helping devices obtain their IP address.

  • Like ARP, it uses Ethernet frames for communication, not IP packets.

  • Therefore, RARP belongs to the Data Link Layer (Layer 2) of the OSI model.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

RARP

RFC

Year

Core Idea / Contribution

Version

RARP v1

RFC 903

1984

Initial specification of RARP. Allowed a device to discover its IP address using its MAC address.

RARP v2 (DRARP)

RFC 1931

1996

Introduced Dynamic RARP

(DRARP), an extension to RARP

for automatic network address

acquisition. It added dynamic

capabilities to the otherwise

static RARP.

  • setup

  • setup

RARP Request Packet

S.No

Protocol Packets

Description

Size(bytes)

1

RARP Request Packet

28

Hardware Type (HTYPE)

type of hardware used for the network (1 for Ethernet).

2

Protocol Type (PTYPE)

type of protocol address being mapped ( 0x0800 for IPv4).

2

Hardware Address Length (HLEN)

length of the hardware address (6 for Ethernet).

1

Protocol Address Length (PLEN)

length of the protocol address (4 for IPv4).

1

Operation (OPER)

Specifies the type of RARP message (3 for request, 4 for reply).

2

Sender Hardware Address (SHA)

MAC address of the sender.

6

Sender Protocol Address (SPA)

IP address of the sender (set to 0.0.0.0 in RARP requests).

4

Target Hardware Address (THA)

MAC address of the target.

6

Target Protocol Address (TPA)

IP address of the target (set to 0.0.0.0 in RARP requests).

4

RARP Reply Packet

S.No

Protocol Packets

Description

Size(bytes)

2

RARP Reply Packet

28

Hardware Type (HTYPE)

type of hardware used for the network (1 for Ethernet).

2

Protocol Type (PTYPE)

type of protocol address being mapped ( 0x0800 for IPv4).

2

Hardware Address Length (HLEN)

length of the hardware address (6 for Ethernet).

1

Protocol Address Length (PLEN)

length of the protocol address (4 for IPv4).

1

Operation (OPER)

Specifies the type of RARP message (3 for request, 4 for reply).

2

Sender Hardware Address (SHA)

MAC address of the sender.

6

Sender Protocol Address (SPA)

IP address of the sender

4

Target Hardware Address (THA)

MAC address of the target.

6

Target Protocol Address (TPA)

IP address of the target

4

S.no

Use Case

Description

1

Diskless Workstations

RARP was primarily used by diskless systems to obtain their IP

address at boot time using their MAC address.

2

Network Booting

Devices without local storage used RARP to fetch

IP addresses before loading an OS over the network.

3

Embedded Systems

Early embedded devices with limited configuration interfaces

used RARP for automatic IP assignment.

4

Legacy Network Environments

Older networks that predate DHCP or BOOTP sometimes still use

RARP for backward compatibility.

5

Simplified IP Configuration

In small or static networks, RARP provided a simple way to assign IPs

without a full DHCP setup.

S.no

Feature

Description

1

MAC-to-IP Resolution

RARP allows a device to discover its IP address using its known MAC address.

2

Operates at Data Link Layer

RARP functions at the OSI Layer 2, using Ethernet frames for

communication.

3

Stateless Protocol

RARP does not maintain session state; it simply responds to requests.

4

Broadcast-Based Request

RARP requests are broadcast on the local network to reach a RARP server.

5

Server-Dependent

Requires a RARP server on the same local network to respond to requests.

6

Limited to IPv4

RARP was designed for IPv4 and does not support IPv6.

7

No Support for Dynamic Allocation

Unlike DHCP, RARP does not dynamically assign IP addresses.

MAC to IP resolution - Testcases

#

Test Case

Description

Expected Result

1

Valid MAC address

Known MAC in server table

Correct IP returned

2

Unknown MAC address

MAC not in server table

No IP returned

3

Broadcast request

RARP request sent as broadcast

Server receives request

4

Unicast request

RARP request sent directly

Server responds if MAC matches

5

Duplicate MACs

Same MAC mapped to multiple IPs

Conflict or error

6

Static mapping

MAC-IP mapping preconfigured

IP returned

7

Dynamic mapping

Server assigns IP dynamically

IP returned

8

Server timeout

Server delays response

Client times out

9

Server unreachable

Network issue

No response

10

MAC spoofing

Fake MAC used

Incorrect or no IP returned

11

Server restart

Server rebooted

Service resumes

12

Retry mechanism

No response initially

Client retries

13

High load

Many requests at once

Server handles load

14

Logging enabled

Server logs requests

MAC-IP logged

15

MAC filtering

Server blocks certain MACs

No IP returned

16

VLAN environment

RARP over VLAN

IP returned if server reachable

17

Trunk port

RARP over trunk

IP returned if VLAN allowed

18

Wi-Fi client

Wireless device sends RARP

Not supported

19

Loopback interface

RARP on loopback

Not applicable

20

PPP link

RARP over PPP

Not supported

21

IPv6-only network

No IPv4

RARP not supported

22

IPv4 network

Standard environment

IP returned

23

BOOTP server present

BOOTP enabled

RARP ignored

24

DHCP server present

DHCP enabled

RARP ignored

25

Proxy in path

Proxy between client/server

No effect

26

NAT environment

Behind NAT

Not applicable

27

MAC address format

Valid 48-bit MAC

Accepted

28

Invalid MAC format

Incorrect length

Rejected

29

Ethernet frame valid

Proper RARP frame

Recognized

30

Corrupted frame

Malformed packet

Ignored

31

RARP daemon active

Server running RARP service

Responds correctly

32

Firewall on server

RARP blocked

No response

33

Firewall on client

RARP blocked

No request sent

34

Port security enabled

Switch limits MACs

May block request

35

Spanning tree delay

STP convergence

Request delayed

36

Link aggregation

Bonded interfaces

MAC must match

37

Virtual MAC

Virtualized environment

IP returned if mapped

38

Container MAC

Docker/LXC

Depends on bridge config

39

Hypervisor MAC

VM requests IP

IP returned if supported

40

PXE boot

Bootloader uses RARP

IP assigned

41

Embedded device

IoT or firmware

IP assigned

42

Legacy OS

UNIX/Linux

RARP supported

43

Modern OS

Windows/macOS/Linux

RARP deprecated

44

MAC in ARP cache

Already resolved

RARP not needed

45

MAC not in ARP cache

Unknown MAC

RARP used

46

MAC-IP mismatch

Wrong mapping

Incorrect IP or error

47

Server with ARP only

No RARP support

No response

48

Server with RARP + ARP

Dual support

RARP handled correctly

49

MAC address case sensitivity

Upper/lowercase MAC

Handled correctly

50

MAC address collision

Duplicate MACs on network

Unpredictable result

Data Link Layer - Testcases

#

Test Case

Description

Expected Result

1

Ethernet frame format

RARP uses Ethernet frame

Frame recognized

2

No IP stack

Client has no IP layer

RARP still functions

3

Layer 2 broadcast

RARP sent as Ethernet broadcast

All devices receive

4

Layer 2 unicast

RARP sent to specific MAC

Only target receives

5

MAC address only

No IP in request

Valid RARP behavior

6

No Layer 3 headers

No IP/TCP/UDP

Valid RARP frame

7

Use of EtherType 0x8035

RARP EtherType used

Frame identified as RARP

8

Switch forwarding

Ethernet switch forwards RARP

Frame delivered

9

Hub broadcasting

Ethernet hub broadcasts RARP

All ports receive

10

VLAN tagging

RARP over 802.1Q VLAN

Frame delivered if VLAN allowed

11

Trunk port

RARP over trunk

Delivered if VLAN tagged

12

MAC filtering

Switch filters MAC

RARP blocked

13

Port security

Switch limits MACs

RARP may be dropped

14

STP delay

Spanning Tree Protocol active

RARP delayed

15

MAC learning

Switch learns MAC from RARP

MAC table updated

16

MAC aging

MAC entry expires

RARP triggers relearning

17

Frame size check

Ethernet frame within limits

Frame accepted

18

Jumbo frame

Oversized RARP frame

May be dropped

19

Frame CRC error

Corrupted Ethernet frame

Dropped by NIC

20

NIC promiscuous mode

NIC captures all frames

RARP visible

21

NIC filtering

NIC filters non-IP frames

RARP may be ignored

22

Wireshark capture

Capture Ethernet traffic

RARP frame visible

23

MAC spoofing

Fake MAC in RARP

May cause conflict

24

MAC collision

Duplicate MACs

Unpredictable behavior

25

Ethernet loop

RARP in looped network

May cause broadcast storm

26

Bridge forwarding

Ethernet bridge forwards RARP

Frame delivered

27

Layer 2 firewall

Filters Ethernet frames

RARP may be blocked

28

Ethernet over USB

RARP over USB Ethernet

Frame delivered

29

Ethernet over fiber

RARP over fiber NIC

Frame delivered

30

Ethernet over coax

Legacy network

RARP supported

31

Virtual NIC

RARP from VM

Frame sent

32

Container NIC

RARP from container

Frame sent if bridged

33

Hypervisor bridge

RARP through virtual switch

Frame forwarded

34

MAC address case

Upper/lowercase MAC

Handled correctly

35

MAC address length

48-bit MAC required

Valid frame

36

Non-Ethernet media

Token Ring/FDDI

RARP not supported

37

Ethernet II frame

Standard frame format

RARP supported

38

802.3 frame

With LLC header

RARP may not be recognized

39

Ethernet encapsulation

RARP inside Ethernet

Valid

40

Ethernet loopback

RARP to self

Frame received

41

Ethernet multicast

RARP not multicast

Frame ignored

42

Ethernet broadcast storm

Excessive RARP

Network congestion

43

Ethernet frame priority

QoS tagging

RARP unaffected

44

Ethernet frame padding

Short frame padded

Still valid

45

Ethernet frame replay

Duplicate RARP

May be ignored

46

Ethernet frame delay

Network latency

RARP delayed

47

Ethernet frame loss

Dropped frame

RARP retry needed

48

Ethernet frame duplication

Same RARP sent twice

One response expected

49

Ethernet frame inspection

Analyze with tool

RARP frame visible

50

Ethernet frame injection

Inject RARP manually

Server responds if valid

Statless Protocol - Testcases

#

Test Case

Description

Expected Result

1

Single request

Send one RARP request

Server responds without storing state

2

Multiple requests

Send repeated RARP requests

Each handled independently

3

No session tracking

Server receives request

No session ID maintained

4

No connection setup

No handshake

Request processed statelessly

5

No connection teardown

No session close

Stateless behavior

6

Request from same MAC

Send twice

Same response, no memory of first

7

Request from different MACs

Multiple clients

Each handled independently

8

Server reboot

Restart server

No session loss (stateless)

9

Client reboot

Restart client

Server still responds

10

No cookies or tokens

No session tokens used

Stateless confirmed

11

No authentication

No login required

Stateless operation

12

No session timeout

No idle timeout

Stateless behavior

13

No session logs

Server logs requests only

No session tracking

14

No session cache

Server does not cache sessions

Stateless confirmed

15

No session reuse

Each request is fresh

No reuse of state

16

No session ID in packet

Inspect RARP frame

No session identifier

17

Stateless under load

High volume of requests

Server handles all independently

18

Stateless after delay

Wait before sending

Server still responds

19

Stateless across VLANs

Requests from different VLANs

Each handled separately

20

Stateless with spoofed MAC

Fake MAC used

Treated as new request

21

Stateless with duplicate MACs

Same MAC from two clients

No conflict tracking

22

Stateless with retry

Client retries request

Server responds again

23

Stateless with dropped packet

Packet lost

No state retained

24

Stateless with malformed packet

Invalid frame

Dropped without state

25

Stateless with broadcast

Multiple clients broadcast

Each handled independently

26

Stateless with unicast

Direct request

Still stateless

27

Stateless with firewall

Firewall blocks request

No state retained

28

Stateless with NAT

Behind NAT

No session tracking

29

Stateless with proxy

Proxy forwards request

Server unaware of proxy

30

Stateless with VLAN hopping

MAC appears on different VLAN

Treated as new request

31

Stateless with MAC change

Client changes MAC

New request processed

32

Stateless with virtual MAC

VM sends request

Treated independently

33

Stateless with container MAC

Docker container sends

No state retained

34

Stateless with hypervisor

VM restarts

Server responds again

35

Stateless with PXE boot

Bootloader sends RARP

Server responds statelessly

36

Stateless with embedded device

IoT device sends RARP

Stateless response

37

Stateless with legacy OS

Old UNIX system

Stateless behavior

38

Stateless with modern OS

Linux/macOS

Stateless behavior

39

Stateless with logging enabled

Server logs request

No session info stored

40

Stateless with monitoring tool

Observe traffic

No session state seen

41

Stateless with duplicate requests

Same request twice

Same response

42

Stateless with delayed response

Server slow

Still stateless

43

Stateless with multiple interfaces

Server has many NICs

Each request handled statelessly

44

Stateless with MAC flooding

Many MACs send RARP

Server handles all

45

Stateless with spoofed server

Fake server responds

No session validation

46

Stateless with ARP cache

Client caches IP

Server remains stateless

47

Stateless with no cache

Client does not cache

Server still stateless

48

Stateless with switch reboot

Network switch restarts

Server unaffected

49

Stateless with packet replay

Replay old RARP

Server responds again

50

Stateless with no response

Server down

No session error, just no reply

Broadcast based Req - Testcases

#

Test Case

Description

Expected Result

1

Standard broadcast

RARP sent to FF:FF:FF:FF:FF:FF

All devices receive

2

Server on same subnet

RARP broadcast sent

Server responds

3

Server on different subnet

RARP broadcast sent

No response (not routed)

4

Broadcast blocked by switch

Switch filters broadcast

RARP fails

5

Broadcast storm

Excessive RARP broadcasts

Network congestion

6

Broadcast with VLAN tag

Tagged Ethernet frame

Delivered if VLAN allowed

7

Broadcast with trunk port

Sent over trunk

Delivered if VLAN permitted

8

Broadcast with port security

Switch limits MACs

May block RARP

9

Broadcast with STP delay

Spanning Tree convergence

RARP delayed

10

Broadcast with loop prevention

Loop guard active

RARP delivered safely

11

Broadcast with firewall

Firewall blocks Layer 2

RARP blocked

12

Broadcast with Wireshark

Capture RARP broadcast

Frame visible

13

Broadcast with packet sniffer

Monitor network

RARP frame detected

14

Broadcast with multiple servers

All receive RARP

First to respond is used

15

Broadcast with no server

No RARP server present

No response

16

Broadcast with spoofed MAC

Fake MAC in request

Server may respond

17

Broadcast with invalid frame

Malformed RARP

Dropped by devices

18

Broadcast with valid frame

Proper RARP format

Delivered successfully

19

Broadcast with duplicate MACs

Same MAC from two devices

Unpredictable behavior

20

Broadcast with virtual MAC

VM sends RARP

Delivered if bridged

21

Broadcast with container MAC

Docker container sends

Delivered if bridged

22

Broadcast with hypervisor

VM sends RARP

Delivered to server

23

Broadcast with PXE boot

Bootloader sends RARP

Server responds

24

Broadcast with embedded device

IoT device sends RARP

Server responds

25

Broadcast with legacy OS

UNIX/Linux

RARP broadcast supported

26

Broadcast with modern OS

Windows/macOS

RARP deprecated

27

Broadcast with ARP cache

MAC already known

RARP still broadcast

28

Broadcast with no ARP cache

MAC unknown

RARP broadcast sent

29

Broadcast with retry

No response initially

RARP rebroadcasted

30

Broadcast with delay

Network latency

RARP delayed

31

Broadcast with loss

Frame dropped

RARP retried

32

Broadcast with duplication

Same RARP sent twice

Server responds again

33

Broadcast with inspection tool

Analyze Ethernet

RARP frame visible

34

Broadcast with injection tool

Inject RARP manually

Server responds

35

Broadcast with MAC filtering

Switch filters MAC

RARP blocked

36

Broadcast with multicast filter

Multicast filter active

RARP unaffected

37

Broadcast with loopback

Sent to self

Not applicable

38

Broadcast with NAT

Behind NAT

RARP not routed

39

Broadcast with proxy

Proxy in path

No effect on Layer 2

40

Broadcast with DHCP server

DHCP present

RARP still broadcast

41

Broadcast with BOOTP server

BOOTP present

RARP still broadcast

42

Broadcast with IPv6-only network

No IPv4

RARP not supported

43

Broadcast with IPv4 network

Standard LAN

RARP supported

44

Broadcast with Ethernet II

Standard frame

RARP supported

45

Broadcast with 802.3 frame

LLC header present

RARP may not be recognized

46

Broadcast with CRC error

Corrupted frame

Dropped

47

Broadcast with short frame

Padding added

Still valid

48

Broadcast with jumbo frame

Oversized frame

May be dropped

49

Broadcast with QoS tag

Priority tagging

RARP unaffected

50

Broadcast with MAC learning

Switch learns MAC

MAC table updated

Server Dependent - Testcases

#

Test Case

Description

Expected Result

1

Server available

RARP server on LAN

IP address returned

2

No server present

No RARP server

No response

3

Server on different subnet

Not on same LAN

No response

4

Server powered off

Server offline

No response

5

Server rebooted

Server restarts

Service resumes

6

Server with firewall

RARP blocked

No response

7

Server with RARP daemon

Service running

Responds correctly

8

Server with ARP only

No RARP support

No response

9

Server with DHCP only

No RARP support

No response

10

Server with BOOTP only

No RARP support

No response

11

Server with RARP + ARP

Dual support

RARP handled

12

Server with logging

Logs RARP requests

Entries recorded

13

Server with MAC filtering

Blocks certain MACs

No response

14

Server with static mapping

Predefined MAC-IP

IP returned

15

Server with dynamic mapping

Assigns IP on request

IP returned

16

Server with duplicate MACs

Same MAC mapped twice

Conflict or error

17

Server under load

High request volume

Responds if not overloaded

18

Server with retry logic

Handles repeated requests

Responds consistently

19

Server with VLAN config

On same VLAN

Responds

20

Server on trunk port

Tagged VLANs

Responds if VLAN allowed

21

Server with port security

MAC limited

May block request

22

Server with STP delay

Spanning Tree active

Response delayed

23

Server with loop prevention

Loop guard enabled

Responds safely

24

Server with virtual NIC

VM-based server

Responds if bridged

25

Server with container NIC

Docker-based server

Responds if bridged

26

Server with hypervisor

Hosted on VM

Responds if networked

27

Server with PXE support

Bootloader requests

Responds with IP

28

Server with embedded device

Lightweight RARP server

Responds correctly

29

Server with legacy OS

UNIX/Linux

RARP supported

30

Server with modern OS

Windows/macOS

RARP deprecated

31

Server with NAT

Behind NAT

No response (Layer 2)

32

Server with proxy

Proxy in path

No effect

33

Server with MAC spoofing

Fake MAC in table

Responds incorrectly

34

Server with duplicate IPs

Same IP mapped to multiple MACs

Conflict

35

Server with ARP cache

MAC-IP already known

Still responds

36

Server with no ARP cache

Fresh request

Responds normally

37

Server with packet sniffer

Monitor RARP

Request visible

38

Server with injection tool

Inject RARP manually

Server responds

39

Server with invalid frame

Malformed RARP

Dropped

40

Server with valid frame

Proper RARP

Responds correctly

41

Server with CRC error

Corrupted frame

Dropped

42

Server with short frame

Padding added

Still valid

43

Server with jumbo frame

Oversized RARP

May be dropped

44

Server with QoS tag

Priority tagging

RARP unaffected

45

Server with MAC learning

Learns from RARP

MAC table updated

46

Server with MAC aging

Entry expires

Still responds

47

Server with duplicate requests

Same request twice

Responds again

48

Server with delayed response

Slow server

Client may retry

49

Server with broadcast filter

Blocks Layer 2 broadcast

No response

50

Server with compliance check

Audit RARP behavior

Server dependency confirmed

Limited to IPv4 - Testcases

#

Test Case

Description

Expected Result

1

IPv4 network

Standard IPv4 LAN

RARP functions correctly

2

IPv6-only network

No IPv4 configured

RARP fails

3

Dual-stack network

IPv4 + IPv6

RARP works only with IPv4

4

IPv6 address request

Client requests IPv6

RARP does not respond

5

IPv4 address request

Client requests IPv4

RARP responds

6

IPv6-only client

No IPv4 stack

Cannot use RARP

7

IPv4-only client

No IPv6 stack

RARP supported

8

IPv6-enabled server

RARP server supports IPv6

Still only responds to IPv4

9

IPv6 broadcast

RARP sent over IPv6

Not supported

10

IPv6 multicast

RARP sent as multicast

Not supported

11

IPv6 tunneling

RARP over IPv6 tunnel

Not supported

12

IPv6 router

RARP request routed

Not possible (Layer 2 only)

13

IPv6 firewall

Filters IPv6 traffic

No effect on RARP

14

IPv6 DNS resolution

Uses AAAA records

RARP not involved

15

IPv6 SLAAC

Stateless address config

RARP not used

16

IPv6 DHCPv6

Dynamic IPv6 assignment

RARP not used

17

IPv6-only switch

No IPv4 support

RARP not supported

18

IPv6-only OS

No IPv4 stack

RARP fails

19

IPv6-only NIC

No IPv4 support

RARP not supported

20

IPv6-only embedded device

No IPv4

RARP not supported

21

IPv6-only VM

Virtual machine with IPv6

RARP not supported

22

IPv6-only container

Docker container

RARP not supported

23

IPv6-only PXE boot

Bootloader uses IPv6

RARP not supported

24

IPv6-only IoT device

No IPv4

RARP not supported

25

IPv6-only hypervisor

No IPv4 stack

RARP not supported

26

IPv6-only VLAN

VLAN configured for IPv6

RARP not supported

27

IPv6-only trunk port

Tagged IPv6 VLANs

RARP not supported

28

IPv6-only router advertisement

RA messages

RARP not used

29

IPv6-only DHCP relay

IPv6 relay agent

RARP not used

30

IPv6-only DNS server

No A records

RARP not used

31

IPv6-only NAT64

IPv6 to IPv4 translation

RARP not supported

32

IPv6-only firewall rules

IPv6 ACLs

RARP unaffected

33

IPv6-only monitoring

IPv6 traffic analysis

RARP not visible

34

IPv6-only packet capture

Capture IPv6 only

RARP not seen

35

IPv6-only testbed

IPv6-only lab

RARP fails

36

IPv6-only compliance

IPv6-only policy

RARP not compliant

37

IPv6-only security scan

IPv6 scan tools

RARP not detected

38

IPv6-only audit

IPv6-only network audit

RARP unsupported

39

IPv6-only switch ACL

Filters IPv6

RARP unaffected

40

IPv6-only routing table

No IPv4 routes

RARP not routed

41

IPv6-only DNS resolver

No IPv4 fallback

RARP not used

42

IPv6-only DHCPv6 server

No IPv4 pool

RARP not used

43

IPv6-only VPN

IPv6 tunnel

RARP not supported

44

IPv6-only cloud instance

No IPv4 address

RARP not supported

45

IPv6-only mobile device

No IPv4 stack

RARP not supported

46

IPv6-only wireless controller

IPv6-only config

RARP not supported

47

IPv6-only RADIUS server

Auth over IPv6

RARP not used

48

IPv6-only syslog server

Logs IPv6 traffic

RARP not logged

49

IPv6-only SNMP monitoring

IPv6 MIBs

RARP not monitored

50

IPv6-only compliance scanner

IPv6-only scan

RARP not detected

No Support for Dynamic Allocation - Testcases

#

Test Case

Description

Expected Result

1

Static MAC-IP mapping

Predefined entry in server

IP returned

2

No mapping in server

MAC not listed

No IP assigned

3

Request from new MAC

Unknown MAC address

No IP assigned

4

Request from known MAC

Listed in server

IP returned

5

Change MAC address

New MAC not mapped

No IP assigned

6

Duplicate MACs

Same MAC on two devices

Conflict or error

7

Server with DHCP

DHCP enabled

RARP still static

8

Server with BOOTP

BOOTP enabled

RARP still static

9

Server with dynamic pool

Pool configured

RARP does not use it

10

Server with static table

Fixed entries

RARP uses only static

11

Client with no mapping

MAC not in table

No IP assigned

12

Client with mapping

MAC in table

IP returned

13

Mapping update

Change IP for MAC

New IP returned

14

Mapping removal

Delete MAC entry

No IP assigned

15

Mapping conflict

Two MACs mapped to same IP

Conflict

16

Mapping duplication

Same MAC mapped to two IPs

Conflict

17

Server restart

Static table reloaded

IPs still assigned

18

Server with empty table

No entries

No IPs assigned

19

Server with full table

All MACs mapped

Only listed MACs get IPs

20

Server with expired entry

Entry removed

No IP assigned

21

Server with lease time

Lease expires

RARP unaffected

22

Server with dynamic assignment enabled

DHCP active

RARP ignores it

23

Client retries

Repeated requests

Same IP returned

24

Client spoofing MAC

Fake MAC used

IP returned if mapped

25

Client with multiple NICs

Different MACs

Each needs mapping

26

Client with virtual MAC

VM MAC address

IP returned if mapped

27

Client with container MAC

Docker MAC

IP returned if mapped

28

Client with hypervisor MAC

Virtualized MAC

IP returned if mapped

29

Client with embedded MAC

IoT device

IP returned if mapped

30

Client with PXE boot

Bootloader MAC

IP returned if mapped

31

Client with legacy OS

UNIX/Linux

RARP works with static mapping

32

Client with modern OS

Windows/macOS

RARP deprecated

33

Server with MAC filtering

Only listed MACs allowed

Others blocked

34

Server with logging

Logs static assignments

Entries recorded

35

Server with monitoring

Tracks MAC-IP usage

Static only

36

Server with SNMP

Monitors static table

No dynamic data

37

Server with API

Static table managed via API

RARP uses updated table

38

Server with GUI

Admin updates static table

RARP uses new entries

39

Server with CLI

Static entries added via CLI

RARP uses them

40

Server with config file

Static table in file

RARP reads from file

41

Server with database

Static mappings stored in DB

RARP queries DB

42

Server with backup

Static table backed up

Restored after reboot

43

Server with failover

Secondary server has same table

IPs still assigned

44

Server with sync

Static tables synced

Consistent IP assignment

45

Server with audit log

Tracks static assignments

No dynamic logs

46

Server with compliance check

Static-only policy

RARP passes

47

Server with security scan

Scan for dynamic behavior

RARP flagged as static

48

Server with DHCP fallback

DHCP used if RARP fails

RARP still static

49

Server with MAC aging

MACs expire

RARP unaffected

50

Server with dynamic override

Admin tries dynamic config

RARP ignores it

  • Reference links