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Why would a host/user send arp requests to all IP addresses in the entire range?

asked 2021-08-12 07:29:21 +0000

Currently I'm seeing broadcast traffic sent from a single host to every IP address, which can not be normal behavior given it won't be "looking" for each IP. Note that this is /22 as well, so it cycles through all IP's, asking "Who has...?"

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answered 2021-08-12 09:54:02 +0000

hugo.vanderkooij gravatar image

That is ARP working as it should. Why that host insists on polling each and every host in it's local subnet is something you need to investigate on the machine itself.

But it could be something as silly as defining a network printer by name and not the IP address. If th machine can't resolve the name it will poll each host on your network t find the printer.

Can you imagine what hapens to a switched network if you use as local network?

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A /8 would be painful indeed, thanks for input

Cross213 gravatar imageCross213 ( 2021-08-12 11:40:16 +0000 )edit

answered 2021-08-12 10:52:37 +0000

BigFatCat gravatar image

That is unusual behavior. Hosts don't normally scan the entire subnet. The host should only send ARP when it needs a MAC address for an IP address. It is either a software bug, or installed software trying to find out what is connected to the network.

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This is true and noted, I will have to check the host for anomalies, thanks.

Cross213 gravatar imageCross213 ( 2021-08-12 11:39:51 +0000 )edit

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Asked: 2021-08-12 07:29:21 +0000

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Last updated: Aug 12 '21