When the DF bit is set, which two actions will a router perform by default on a packet that is larger than the MTU of the interface? (Choose two.)
A.
The router drops the packet.
B.
The router sends an ICMP MTU exceeded message to the source.
C.
The router fragments and forwards the packet.
D.
The router generates a syslog message indicating that a packet was dropped due to the exceeded MTU.
Explanation:
Packets larger than the interface’s MTU must be fragmented by the router into two or more smaller packets. If a packet is received which has the Don’t Fragment (DF) bit set in the packet header, the packet is not fragmented, but instead discarded. In this case, an ICMP error message is returned to the sender (i.e. to the original packet’s IP source address) informing it of the interface’s MTU size. This forms the basis for Path MTU discovery (PMTU).