Repeater is hardware device which is used to re-generate the clean and brand new and strong signal in the cable.
The repeater does not amplify the signal,because when repeater amplify the signal it might amplify the noise that is picked up along the way.You know ethernet cable can transmit the signal in the electrical form upto 100 meter, after that signal goes weaker and weaker, and cable is unable to transmit the data, So we use repeater to cover up the longer distance than 100 meter.
picture source:http://www.kollewin.com/blog/repeater-ethernet/
**********************************************************************************ARP (Address Resolution Protocol)
The Address Resolution Protocol is used to mapping from the 32 bit IP addresses to 48 bit MAC addresses.
ARP maps the IP address to MAC address and RARP (Reverse Address Resolution Protocol) is used the MAC address to find the IP address.
ARP uses four types of Packets:
1. ARP Request
2. ARP Reply.
3. RARP Request
4. RARP Reply
ARP Cache:
To reduce the number of address resolution requests,thereby minimizing network utilization, a client caches resolved addresses for a short time.This table is known as ARP cache,is used to maintain mapping between each MAC address and its corresponding IP address locally.
Entries ARP cache can be viewed, added and deletedby using ARP utility in CMD Prompt.
To view ARP cache: C:\>arp -a
To filter the display address listing based upon a specific interface, use -n option.
e.g. arp -a -n <interface>
To add manually entries: arp -s <IP Address> <MAC address>
To view cache of particular IP address: arp -a <IP address>
Source:Network+ book by TATA McgrawHill
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