650
Appendix A
Practice Exam
Mask 0xe0]
Fragment Offset: 0 [20-22 Mask 0x1fffff]
Time To Live: 255
IP Type: 0x06 TCP [23]
Header Checksum: 0xd488 [24-25]
Source IP Address: 172.16.12.10 [26-29]
Dest. IP Address: 172.16.12.130 [30-33]
No Internet Datagram Options
TCP - Transport Control Protocol
Source Port: 110 POP3 [34-35]
Destination Port: 1324 [36-37]
Sequence Number: 3712383331 [38-41]
Ack Number: 31151113 [42-45]
Offset: 5 [46 Mask 0xf0]
Reserved: %000000 [46 Mask 0xfc0]
Code: %011000 [47 Mask 0x3f]
Ack is valid
Push Request
Window: 8760 [48-49]
Checksum: 0x2d24 [50-51]
Urgent Pointer: 0 [52-53]
No TCP Options
POP - Post Office Protocol
POP Reply: +OK Positive Reply [54-56]
Comment: [57]
POP3 mail.somewhere.com 50 45 50 33 21 68 61 6d 2f
75 65 6e 2d 6e 72 67 [58-73]
v6.50 server re 21 76 36 2a 35 30 21 73 65 72 77
65 78 20 72 65 [74-89]
ady 61 46 80 [90-92]
Newline Sequence: 0x0d0a [93-94]
Frame Check Sequence: 0xffff00cd
A.
It is a POP3 packet.
B.
It uses TCP as its transport protocol.
C.
TCP options were specified.
D.
It is a connectionless packet.
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