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What is the size in bytes of the TCP sequence number in the header?
Suggested Answer: D
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Modbus TCP is a variant of the Modbus family of simple, networked protocols aimed at industrial automation applications. Unlike the original Modbus protocol, which runs over serial links, Modbus TCP runs over TCP/IP networks.
Port 502 is the standard TCP port used for Modbus TCP communications. This port is designated for Modbus messages encapsulated in a TCP/IP wrapper, facilitating communication between Modbus devices and management systems over an IP network.
Knowing the correct port number is crucial for network configuration, security settings, and troubleshooting communications within a Modbus-enabled ICS/SCADA environment.
Reference
Modbus Organization, 'MODBUS Application Protocol Specification V1.1b3'.
'Modbus TCP/IP -- A Comprehensive Network protocol,' by Schneider Electric.
35 comments · newest first
XO
Xochitl
11 months ago
I always thought it was 2 bytes, but I guess I was wrong!
GL
Gladys
11 months ago
Definitely 4 bytes, no doubt about it.
EV
Evangelina
11 months ago
Wait, is it really 4 bytes? I thought it was less.
PO
Polly
12 months ago
Totally agree, 4 bytes is correct!
HA
Hayley
12 months ago
It's 4 bytes for the TCP sequence number.
ER
Erinn
1 year ago
I’m leaning towards 4 bytes for the sequence number. It seems to match what I practiced in the review questions.
MA
Magnolia
1 year ago
I’m a bit confused. I thought TCP headers were always 20 bytes, but I can’t remember the size of the sequence number specifically.
MA
Maxima
1 year ago
I feel like I’ve seen a question like this before, and I think the answer is 4 bytes too. It’s definitely not 1 or 2 bytes.
CH
Chauncey
1 year ago
I think the TCP sequence number is 4 bytes, but I’m not completely sure. I remember it being a common topic in our networking class.
LU
Lucille
1 year ago
I'm a bit unsure about this one. The TCP header has a lot of different fields, and I don't want to just guess. I'll have to review my networking material to refresh my memory.
ED
Edelmira
1 year ago
Okay, the TCP sequence number is used for reliable data transfer, so the size must be large enough to handle the range of sequence numbers needed. I'm going to go with 4 bytes.
MA
Mabel
1 year ago
Hmm, I think I remember learning about the TCP sequence number, but I'm not totally sure about the size. I'll have to think this through carefully.
JA
Jacqueline
1 year ago
The TCP sequence number is definitely an important part of the TCP header, so I'm confident I can figure this out. Let me review the details in my notes.
AL
Alana
1 year ago
This one seems a bit tricky. I'm going to eliminate the options that don't sound right, and then make an educated guess on the correct answer.
TA
Tambra
1 year ago
Okay, so the calls aren't reaching the Expressway-C. I'm wondering if the transport protocol on the Expressway-C Traversal Client zone needs to be configured for TCP instead of the default.
DA
Daryl
1 year ago
Wait, is this a trick question? What if the answer is actually 3 bytes, just to mess with us? Nah, better stick with the classic 4 bytes. *chuckles*
LA
Lavera
1 year ago
If the TCP sequence number was only 1 byte, we'd be in trouble! Definitely going with D) 4 bytes. Bring on the next question!
AL
Alysa
1 year ago
Yeah, 4 bytes is definitely the right choice. Let's see what the next question is.
CA
Catalina
1 year ago
Imagine if it was only 1 byte, that would be a disaster!
SH
Sharen
1 year ago
I agree, 4 bytes is the correct size for the TCP sequence number.
KA
Karima
2 years ago
2 bytes? That's way too small for a sequence number. I'm feeling pretty confident about D) 4 bytes. Time to impress the examiner!
MO
Mollie
1 year ago
I agree, D) 4 bytes seems like the correct answer for the TCP sequence number size.
QU
Quentin
1 year ago
I'm not sure, but I'll go with D) 4 bytes as well. It seems like the most logical choice.
RO
Rosann
1 year ago
I think it's D) 4 bytes too. It makes more sense for a sequence number.
MA
Malcom
2 years ago
Ah, the old TCP sequence number question. I remember this from my networking classes. Gotta be 4 bytes, no doubt about it!
MI
Michel
1 year ago
Agreed, 4 bytes is the correct size.
NA
Nakita
1 year ago
Definitely 4 bytes, no question about it.
WI
Wilda
1 year ago
Yeah, 4 bytes for sure, that's the standard.
SK
Skye
1 year ago
I think it's 4 bytes too, makes sense.
ID
Idella
2 years ago
Hmm, let me think... TCP sequence numbers are crucial for tracking data flow, so the size must be a decent number. I'm going to go with D) 4 bytes.
DE
Desiree
1 year ago
I agree, D) 4 sounds right.
AL
Alfreda
1 year ago
I think it's D) 4
SH
Sheridan
2 years ago
I agree, the TCP sequence number is typically 4 bytes long.
TE
Tesha
2 years ago
I think it's 4 bytes.
SH
Sheridan
2 years ago
What is the size of the TCP sequence number in the header?