Checking MTU

Check the MTU (Maximum Transmission Unit) of a network interface using the ping command with the Don't Fragment (DF) flag.

1	`ping -M do -s 1472 <destination>`

-M do → Enables the Don't Fragment (DF) flag, preventing packet fragmentation.
-s 1472 → Specifies the payload size (1472 bytes is used for standard Ethernet with an MTU of 1500).

1472

The payload size of 1472 is used because the ICMP header is 8 bytes, and IP header 20 which makes the total packet size 1500 bytes.

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usage

To find the actual MTU, decrease the -s value in steps until you get a successful response.