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Why would you clear ARP cache?
Clearing the ARP cache essentially causes all the requests in your database to go through the entire ARP process again. Basically, every connection you now establish will have to resolve the MAC address from the IP address again.
How does ARP work in HSRP?
HSRP and ARP. HSRP works when the hosts are configured for proxy ARP. When the active HSRP device receives an ARP request for a host that is not on the local LAN, the device replies with the MAC address of the virtual router. If the Hot Standby state of the interface is not active, proxy ARP responses are suppressed.
What is a gratuitous ARP reply?
Gratuitous ARP replies are reply packets sent to the broadcast MAC address with the target IP address set to be the same as the sender’s IP address. When the router or switch receives a gratuitous ARP reply, the router or switch can insert an entry for that reply in the ARP cache.
How long does it take to clear the ARP cache?
Usually takes 2 to 6 minutes depending on the equipment. Analysis of the data will be the principle difficulty here for most of us in discerning when this might be necessary based on symptoms but you can anticipate such troubles if you are replacing one network device with another and assigning the same static IP. 01-04-2014 10:39 PM
Why do you need to clear the APR cache?
Clearing the APR cache will cause all request that were in the ARP cache to go through the APR process again (if the node tries to communicate with them). 05-05-2013 03:43 PM 05-05-2013 03:43 PM that all make sense but still more explaination required to justify our point of view,
Do you need command prompt to clear ARP table?
On a server, you will require an elevated command prompt. On a modem, you will need to run a script (generally this is done by the Internet provider) to clear the ARP table. Modems where static IPs are used will store ARP table data. Switches and routers may also need to be cleared. Rebooting/power cycling may not clear the cache on these devices.
What happens if an active router fails to run HSRP?
If the active router fails, the standby assumes the packet forwarding duties. Although an arbitrary number of routers may run HSRP, only the active router forwards the packets that are sent to the virtual router IP address.