From the FAQ question How do I find my optimum MTU setting? AT&T Southeast Forum FAQ - dslreports.com:

How do I find my optimum MTU setting? (#5793)

Important Recommendation: This FAQ is for pointy headed people with no life that are just dying to get their command prompt fix and do some interesting (albeit completely boring) tests. I strongly recommend you download DrTCP, set your MTU on your NIC(s) to 1492 as shown here, and do something better with your time. That said, if you wish to continue please proceed.


Hey, it's an issue, even.

C:\Users\toBeNamedLater>ping www.google.com -f -l 1475

Pinging www.l.google.com [72.14.205.103] with 1475 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 72.14.205.103:
Packets: Sent = 3, Received = 0, Lost = 3 (100% loss),
Control-C
^C
C:\Users\toBeNamedLater>ping www.google.com -f -l 1473

Pinging www.l.google.com [72.14.205.103] with 1473 bytes of data:

Packet needs to be fragmented but DF set.

Ping statistics for 72.14.205.103:
Packets: Sent = 1, Received = 0, Lost = 1 (100% loss),
Control-C
^C
C:\Users\toBeNamedLater>ping www.google.com -f -l 1472

Pinging www.l.google.com [72.14.205.103] with 1472 bytes of data:

Reply from 72.14.205.103: bytes=56 (sent 1472) time=1981ms TTL=241

Ping statistics for 72.14.205.103:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1981ms, Maximum = 1981ms, Average = 1981ms
Control-C
^C
C:\Users\toBeNamedLater>