Join Greg Sowell for an in-depth discussion in this video ARP and InARP, part of Networking Foundations: Protocols and CLI Tools.
- [Voiceover] When one device is trying to determine…how to send information to another device…on the same layer two network based on a layer three IP…address, a process needs to be performed to do the lookup.…This is facilitated by the address resolution protocol.…ARP was created in 1986 as RFC826.…ARP maps layer three IP addresses…to layer two MAC addresses.…If a host wants to send packets to a neighbor on the same…layer two segment, it will need to ARP for the address.…
If a router needs to forward packets to another router,…the next top router's IP will need to be ARPed…as the information is transferred…via directly connected subnet.…By nature, ARP is a request and response system.…If host one needs to send information to host two,…it will first consult its ARP cache.…This is a table that temporarily…holds IP to MAC information.…If the MAC address is available in the cache,…it will encapsulate the packet into a frame…destined for host two's MAC,…encapsulated into bits and sent on the wire.…
If, however, the cache doesn't hold the entry,…
Protocols are the lifeblood of modern communication. By the end of this course, you'll know what you need to troubleshoot any network connection and keep the communication flowing.
Note: This course maps to domain 3 of the MTA Networking Fundamentals exam.
- Identify reasons why connectionless transmissions are faster.
- Determine what type of attack a gratuitous ARP announcing itself as a legitimate host indicates.
- State what IGMP snooping is useful for.
- Describe the best approach to use FTP to view and rename files on a server when your client is behind a firewall.
- Assess whether SSH is natively supported on Windows or not.
- List good uses for the arp command.