Your ARP cache is overflowing negatively impacting users experience on your network.
Which command can you issue to increase the ARP cache on the fly? You do not need this

to survive reboot.

A.
arp cache table > 1024

B.
echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

C.
You cannot increase the size of the ARP cache on the fly.

D.
Modify the /etc/sysctl.conf: net.ipv4.neigh.default.gc_thresh3 = 1024.