What ARP does | Network Fundamentals Part 15
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- เผยแพร่เมื่อ 20 ก.ค. 2024
- What ARP does | Network Fundamentals Part 15
ARP, or Address Resolution Protocol, provides IP to MAC address mapping services. It works by using two messages, the request and reply.
When a host needs to know the MAC that belongs to an IP, it will broadcast the request message. The device that owns the IP will reply (unicast) with its MAC address. Any other host that gets the message will discard it.
Once the reply has been received, the IP to MAC mapping will be stored in the ARP cache, to make the process faster next time. But if the entry is not used, it will eventually be removed from the cache.
Also of use is GARP, which a host will use to preemptively notify the local network of its IP and MAC address. This increases efficiency.
Quiz: link: networkdirection.net/labsandq...
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In the next few videos, we’re going to have a look at DHCP and DNS.
Overview of this video:
0:00 Introduction
0:26 What does ARP Do?
1:32 How Does ARP Work?
2:20 ARP Cache
3:40 RARP and GARP
LET'S CONNECT
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Try the quiz here!
networkdirection.net/labsandquizzes/quizzes/arp-quiz/
underrated channel.
Last year at the university we studied ARP for hours and we didn't understand it.
Now thnx to u I have a good comprehesion of ARP
Keep up the good work :)
What do you study ?
As usual, well done.
Thanks John!
Nice & short which helps with our attention span. 😅
It's certainly a challenge to keep them short
Love your videos. Would you be willing to share what program you use to make them?
It varies depending on the video, but I primarily use a combination of Power point, blender, and Davinci Resolve
Isn't ARP logic similiar to flooding and aging timer in switches
at 4:36 talking about GARP. Is this how Auto Addressing (or sometimes called Link Local) works? When a device is not using static or DHCP, they "auto address". When they GARP, is that how the communication happens so different IPs are used? Or am I skipping ahead?
Two years too late, but yes, you were skipping ahead. This was mentioned in one of the earlier videos of the series. The automatic IP address is a randomly chosen IP address, only on Windows systems.
How do we learn MAC of an IP in another subnet?
That's a good question. In short, we don't.
MAC addresses are only used within the VLAN/subnet
If you need to access another subnet, that's where your default gateway comes in. It's a router that's connected to both subnets, and passes traffic back and forth as needed
@@NetworkDirection thank you for answering :)
11 740 views and 0 dislikes, I have never seen anything like this before.
41K now. still 0 dislikes
How the RARP and GARP announced? Like ARP used layer 2 broadcast message.
They're a bit outside of the scope of this video. But...
RARP is the reverse of ARP. It's a similar process to get an IP from a MAC
GARP is a notification that's sent out when an IP changes, so all devices are proactively aware
bring back the notes on the video please.
I'm afraid to sound noob.. but isn't that the switch's job? (Matching every IP to its corresponding MAC)
Ao why would the devices need to keep track of them?
Well, partly... The switch keeps a table of MACs so it knows which port to forward a frame out of.
Each host also needs to know MAC addresses. When it sends a packet, it will know the IP that it wants to send it to. It then needs to encapsulate the L3 packet with L2 headers (usually Ethernet), which means it needs to know a destination MAC address. The destination MAC could be the destination host, or the MAC of the default gateway.
ARP helps, as the host can take the IP it already knows, and find the MAC that matches up with it.
I appreciate your response 💙
Btw you're the best networking channel on TH-cam ✌, plz don't stop
you are not done yet, keep going, we will meet at part 26
Thanks for watching our series 😀
@@NetworkDirection oh thank you, it helped me so much, I even got a distinction on my exam last time
Thank you so much🤝
Hey you! Empty ya PAwCKETS! Gimme all ya cAche!
i love you more