Static IP addresses -- destination host unreachable / request timed out

I have 10+ Cisco switches on an old
Windows 2003 DC that will be upgraded soon.

How can I flush ARP cache/etc so the below .90 static IP works again
or could I just keep .90 unplugged for a few days, let the ARP cache
expire, plug it back up, and it should work ?
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Yesterday
o      user needed a static IP and 192.168.24.90 gave a “Request timed out”, showing it was usable
o      turns out something just needed rebooting for it to get assigned the .90 IP
o      changed above user's IP to 192.168.24.92
o      everything seemed to work
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Today
o      below .90 IP has no valid route from the 24.11 Cisco switch since
        router begins sending ARP request packets on its local network,
        asking for the MAC address of a host with an IP address, but is
        confused, therefore .90 IP does not want to work
finance_teacherAsked:
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mikebernhardtCommented:
To clear arp cache on a Cisco switch, just type "clear ip arp" on the switch. I have no idea how to help you on the "Today" part without knowing how things connect, what the subnet is (with subnet mask), and how the switch is configured, whether you have routing enabled, etc.

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Craig BeckCommented:
Just some info first...
Yesterday
o      user needed a static IP and 192.168.24.90 gave a “Request timed out”, showing it was usable
That's not necessarily the case.  If the device is firewalled and is blocking ICMP (for example) the reply will be "Request timed out" but a device will actually be using the .90 address.  Don't always assume "Request timed out" to mean the IP isn't being used.  Always check the ARP table from a device on the same VLAN/subnet as the host you're trying to ping first.

The ARP entry is refreshed after 4 hours on a Cisco switch, so that's unlikely to be your problem.  As well as that, the ARP entry is refreshed 60 seconds before it expires on the switch, so if it was incorrect it would only be incorrect for 3 hours and 59 minutes at most, unless you still have an IP conflict.

It's most likely a gateway issue at the client side.  Can you ping 24.11 from 24.90?
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