Which value is the maximum segment size if you start with an MTU of 1500 bytes and then remove
the overhead of the Ethernet header, IP header, TCP header, and the MAC frame check sequence?
A.
1434 bytes
B.
1460 bytes
C.
1458 bytes
D.
1464 bytes
B is correct.
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TCP = 20 bytes
IP = 20 bytes
Ether Preamble = 8
Ether Source = 6
Ether Dest = 6
Ether type = 2
FCS = 4
Total = 66
1500-66 = 1434
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B is correct. The MTU does not include the Ethernet header or the FCS. They are already discounted when you talk about MTU. So you just need to remove the IP and TCP headers of 20 bytes each which leaves 1460 bytes.
If you have an MTU of 1500 bytes the ethenret frame is actually 1518 bytes on the wire. The other 18 bytes extra that have already been discounted when using the term MTU.
This is a good description.
http://blog.apnic.net/2014/12/15/ip-mtu-and-tcp-mss-missmatch-an-evil-for-network-performance/
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