What does a router change in a packet when it forwards a
packet to the next hop?
* A: Destination physical address
* B: Destination network address
* C: Destination network address and the destination
physical address
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Answer / jitendera kumar sinha
sudeep is correct option is A
here is the explanation
Let's say that we have Host A and Host D. Host A sends a
packet to Host D, which Host D is on a different network.
Host A applies both the logical address and logical device
address before sending the packet. The source network layer
address is also added to the packet, so the receiving device
can reply if it needs to. Then Host A adds it's own device
address (which in this example is 10.) Instead of adding the
device address of Host D, it uses the next router in the
path (which it's address is 20.) Now the packet is sent and
is received by the next router. Router B examines the
destination address and recognizes the address is addressed
to it. The router strips off the data link addresses and
examines the destination device of the network layer. It
recognizes the address to be on a different network. Since
Router C is the next router in the path, Router B sends the
packet to it. So Router B applies it's own device address
(20) and uses Router C device address as the destination
address (30) Router B sends the packet to Router C. Router C
sees that it's addressed to it. Router C strips off the data
link addresses and examines the destination device of the
network. It recognizes that the packet is sent to Host D.
Router C applies it's own device address and applies the
destination address of Host D (40) Router C sends the packet
to Host D. The data link addresses are removed. The original
source and destination addresses are contained in the packet
at the network layer.
hope this article help those people who marked it wrong
| Is This Answer Correct ? | 4 Yes | 0 No |
Answer / mr.shahin07
(10.0.0.1) (10.0.0.2)
S0 S0
(R1)------------------------(R2)
!E0/1 (0ACF:AAA1:000A) ! E0/1 (1ACF:BBA1:010A)
!IP - 172.16.1.100 ! IP - 172.17.1.100
! !
! !
! !
(Host A) (Host B)
E0 (ABC0:ABB1:00A0) E0 (CAA0:ABE1:110A)
IP - 172.16.1.1 IP - 172.17.1.1
Just assume this is a network & all interfaces having their
Layer 2 & Layer 3 addresses.
Now Host A want to send some data to Host B.
Now wat wud be the Layer 2 & 3 source & Destination address.
a) Packet leaving Host A.
Layer 3 Source add - 172.16.1.1
Layer 3 Destination add - 172.17.1.1
Layer 2 Source add - ABC0:ABB1:00A0 (E0 of Host A)
Layer 2 Destination add - 0ACF:AAA1:000A (E0/1 of R1)
b) Packet leaving Router R1 -
Layer 3 Source add - 172.16.1.1
Layer 3 Destination add - 172.17.1.1
Layer 2 Source add - 0ACF:AAA1:000A (E0/1 of R1)
Layer 2 Destination add - 1ACF:BBA1:010A (E0/1 of R2)
c) Packet leaving Router R2 -
Layer 3 Source add - 172.16.1.1
Layer 3 Destination add - 172.17.1.1
Layer 2 Source add - 1ACF:BBA1:010A (E0/1 of R2)
Layer 2 Destination add - CAA0:ABE1:110A (E0/1 of R2)
So every time DESTINATION PHYSICAL ADDRESS is changed.
Hi guys, i just share wat i know. Let me if i m wrong. Your
feedback is important for me.
With Thanx & Regards
Shahin Ahmed
| Is This Answer Correct ? | 5 Yes | 1 No |
Answer / aurel
Shahin 07
You make it clear and easy to get. Many thanks !
| Is This Answer Correct ? | 2 Yes | 0 No |
Answer / jitendera kumar sinha
ha ha thanks shain for supporting me and providing the scenario based explanation people don't like to read theory so this article help them more.i mark it as excellent
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / gyan
TTL will also be decremented by 1 on each router before forwarding.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / jitendera kumar sinha
but sahin if u make your answer with three router (R1 R2 and R3)and host off R1 want to send the data to R3 through R2 then it will easy to understandble.meanwhile it is excellent
| Is This Answer Correct ? | 0 Yes | 0 No |
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