When static ARP is configured, the router explicitly binds an IP address to a specific MAC address. This means:
If the MAC address of the device changes (as it does when a new network card is installed), and the IP remains the same, the router will not allow the device to communicate, because the MAC address in the ARP table no longer matches the new hardware.
Options explained:
A.✔Correct. The old ARP entry must be updated to reflect the new MAC address if the IP is reused.
B.✘Incorrect. The communication will fail if the ARP table still holds the outdated MAC for that IP.
C.✔Correct. Alternatively, if the new NIC supports MAC address modification, setting the MAC address to match the old one would make the static ARP entry valid again.
D.✘Incorrect. There's no need to change the IP if the static ARP entry is updated.
Extract from Official MTCNA Course Material – ARP Section:
"Static ARP entries tie IPs to MAC addresses. If the MAC changes but the static ARP entry remains unchanged, the device cannot communicate with the router."
Extract from René Meneses MTCNA Study Guide – ARP:
"When using static ARP, any MAC change must be reflected in the router's ARP table; otherwise, packets will be dropped."
Extract from MikroTik Wiki – ARP Modes:
"Static entries require matching MAC addresses. If the client's MAC changes, the ARP table must be updated or communication will fail."
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