WEB EXAM: |COMPLETE STUDY GUIDE WITH 100%
ACCURATE QUESTIONS & ANSWERS | ACE EVERY TEST |
GUARANTEED EXCELLENCE.
ROUTE: Answer: datagram between two network interfaces
Fragment: Answer: datagrams according to physical layer characteristics
MAC Address: Answer: -> unique identifier printed in hardware for network interface
controller
-> six groups of two hexedecimal digits
IPv4 address: Answer: Network prefix-> n bits
host suffix-> n-32
Fragmentation Answer: The breaking process of something that exceeds MTU
-> Fragmentation happens at the network layer, meaning the IP layer
->
Segmentation Answer: -> happens at the transport layer especailly TCP
-> TCP takes application data and splits it into smaller TCP segments
Fragmentation Answer: -> happens at the IP layer
-> it happens when an IP packet is too alrge for the next network link
Who reassembles fragments? Answer: -> Only by the destination
-> this means that when an IP packet is fragmented, the fragments are not reassembled by
routers along the path
-> Routers may forward fragments, and in IPv4 they may even create fragments, but they
usually do not put them back together
When can reassembly happen: Answer: All fragments need to have been delivered
What if one fragment is missing or corrupted? Answer: IP does not have the capability of
requesting a fragment that is missing or corrupted
-> IP is a best effort protocol
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,How does the destination reassemble fragments? Answer: To be able to reassemble fragments,
the destination will use the fragmentation offfset to determine the order in whcih to reassemble
fragments
Identification field: Answer: is used to identify which fragments belong to the same original
datagram
-> So all fragments from the same original datagram have the same identificatio number
-> Identification tells the receiver which fragments belong to the same original packet
MF flag: Answer: -> More Fragments flag
-> It tells the receiver whether more fragments are coming after this one
-> there are two possible values
-> MF =1 (MORE FRAGMENTS ARE COMING)
-> MF = 0 this is the last fragment
fragmentoffsest: Answer: -> Where does this fragment belong inside the original IP datagram
IPv4 vs IPv6: Answer: Size: IPv4: 32 bits
IPv6: 128bits
IPv4: Decimal numbers
IPv6: Hexadecimal numbers
ICMP: Answer: Internet Control Message Protocol
-> It is used by network decices to send control messages and error messages
-> IP does not gaurantee delivery, so ICMP helps by reporting problems
ICMP message types include: Answer: Echo Request: Used by ping "Are you there"
Echo Reply: Used by ping "Yes I am here"
Destination unreachable
Time exceedd
Redirect
Ping: Answer: is a tool used to test whether another device is reachable over the network
TTL: Answer: How many routers a packet is allowed to pass through before being destroyed
->TTL prevents packets from travelling forever
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,-> so TTL protects the network from infinite loops
3. What happens when TTL becomes 0? Answer: When a router receives a packet and TTL
becomes 0:
the router discards the original packet;
the router sends an ICMP Time Exceeded message back to the sender.
Important:
The router does not send the original packet back. It sends a new ICMP error message.
Ping tells you mainly: Answer: whether the destination replies;
how long the round trip takes;
whether packets are lost.
traceroute: Answer: Traceroute is a tool that shows the path packets take through routers.
Subnet MASK Answer: NETWORK PREFEX: 19
MAKE the first 19 digits 1
Network address Answer: making everything except the NEtwork prefix address 0
number of IPv4 available formula Answer: 2 ^32-network -2
TCP messages Answer: 1-Application/ Web data
2- TCP header + 1
3- IP header + 2
4- Frame header + 3
Header Answer: 1- A header identifies the source and destination ports of the message
2- Sequence number: number assigned to the first data byte of this segment
3- Acknowledgement Number: 1+ number of the byte so far acknowledged
4- Window size: is the number of bytes a receiver is ready to receive
Port number: Answer: a process is identified by a host IP address and a port number
socket Answer: IP address + port
MSS Answer: Maximum Segment Size
-> It is the maximum amount of application data that TCP can put inside one TCP segment
-> MSS does NOT include the TCP header
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, MSS does NOT include the IP header
MTU vs MSS: Answer: MTU = MSS + 20 IP header+ 20 TCP header
flow control: Answer: prevents the sender from sending data faster than the receiver can
receive
-> Flow control means controlling the speed of sending data
-> Sender: very fast
-> Receiver: slower computer with limited memory
-> If the sender sends too much data too quickly, the receiver's buffer
receiver window: Answer: tells the sender how much space is still available in the receiver's
buffer: The receiver specifies in the receive window field the amount of additional data, in
bytes, that it is willing to buffer.
sliding window: Answer: Suppose the receiver sends:
ACK = 1000 WINDOW = 500
This means two things.
ACK = 1000
This means:
I have received everything up to byte 999. The next byte I expect is byte 1000.
WINDOW = 500
This means:
I can receive 500 more bytes.
So the sender is allowed to send:
bytes 1000 to 1499
Because:
1000+500−1=14991000 + 500 - 1 = 14991000+500−1=1499
So:
ACK = 1000, WINDOW = 500
means:
You may send bytes 1000-1499.
APPHIA – Crafted with Care and Precision for Academic Excellence.
4
ACCURATE QUESTIONS & ANSWERS | ACE EVERY TEST |
GUARANTEED EXCELLENCE.
ROUTE: Answer: datagram between two network interfaces
Fragment: Answer: datagrams according to physical layer characteristics
MAC Address: Answer: -> unique identifier printed in hardware for network interface
controller
-> six groups of two hexedecimal digits
IPv4 address: Answer: Network prefix-> n bits
host suffix-> n-32
Fragmentation Answer: The breaking process of something that exceeds MTU
-> Fragmentation happens at the network layer, meaning the IP layer
->
Segmentation Answer: -> happens at the transport layer especailly TCP
-> TCP takes application data and splits it into smaller TCP segments
Fragmentation Answer: -> happens at the IP layer
-> it happens when an IP packet is too alrge for the next network link
Who reassembles fragments? Answer: -> Only by the destination
-> this means that when an IP packet is fragmented, the fragments are not reassembled by
routers along the path
-> Routers may forward fragments, and in IPv4 they may even create fragments, but they
usually do not put them back together
When can reassembly happen: Answer: All fragments need to have been delivered
What if one fragment is missing or corrupted? Answer: IP does not have the capability of
requesting a fragment that is missing or corrupted
-> IP is a best effort protocol
APPHIA – Crafted with Care and Precision for Academic Excellence.
1
,How does the destination reassemble fragments? Answer: To be able to reassemble fragments,
the destination will use the fragmentation offfset to determine the order in whcih to reassemble
fragments
Identification field: Answer: is used to identify which fragments belong to the same original
datagram
-> So all fragments from the same original datagram have the same identificatio number
-> Identification tells the receiver which fragments belong to the same original packet
MF flag: Answer: -> More Fragments flag
-> It tells the receiver whether more fragments are coming after this one
-> there are two possible values
-> MF =1 (MORE FRAGMENTS ARE COMING)
-> MF = 0 this is the last fragment
fragmentoffsest: Answer: -> Where does this fragment belong inside the original IP datagram
IPv4 vs IPv6: Answer: Size: IPv4: 32 bits
IPv6: 128bits
IPv4: Decimal numbers
IPv6: Hexadecimal numbers
ICMP: Answer: Internet Control Message Protocol
-> It is used by network decices to send control messages and error messages
-> IP does not gaurantee delivery, so ICMP helps by reporting problems
ICMP message types include: Answer: Echo Request: Used by ping "Are you there"
Echo Reply: Used by ping "Yes I am here"
Destination unreachable
Time exceedd
Redirect
Ping: Answer: is a tool used to test whether another device is reachable over the network
TTL: Answer: How many routers a packet is allowed to pass through before being destroyed
->TTL prevents packets from travelling forever
APPHIA – Crafted with Care and Precision for Academic Excellence.
2
,-> so TTL protects the network from infinite loops
3. What happens when TTL becomes 0? Answer: When a router receives a packet and TTL
becomes 0:
the router discards the original packet;
the router sends an ICMP Time Exceeded message back to the sender.
Important:
The router does not send the original packet back. It sends a new ICMP error message.
Ping tells you mainly: Answer: whether the destination replies;
how long the round trip takes;
whether packets are lost.
traceroute: Answer: Traceroute is a tool that shows the path packets take through routers.
Subnet MASK Answer: NETWORK PREFEX: 19
MAKE the first 19 digits 1
Network address Answer: making everything except the NEtwork prefix address 0
number of IPv4 available formula Answer: 2 ^32-network -2
TCP messages Answer: 1-Application/ Web data
2- TCP header + 1
3- IP header + 2
4- Frame header + 3
Header Answer: 1- A header identifies the source and destination ports of the message
2- Sequence number: number assigned to the first data byte of this segment
3- Acknowledgement Number: 1+ number of the byte so far acknowledged
4- Window size: is the number of bytes a receiver is ready to receive
Port number: Answer: a process is identified by a host IP address and a port number
socket Answer: IP address + port
MSS Answer: Maximum Segment Size
-> It is the maximum amount of application data that TCP can put inside one TCP segment
-> MSS does NOT include the TCP header
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, MSS does NOT include the IP header
MTU vs MSS: Answer: MTU = MSS + 20 IP header+ 20 TCP header
flow control: Answer: prevents the sender from sending data faster than the receiver can
receive
-> Flow control means controlling the speed of sending data
-> Sender: very fast
-> Receiver: slower computer with limited memory
-> If the sender sends too much data too quickly, the receiver's buffer
receiver window: Answer: tells the sender how much space is still available in the receiver's
buffer: The receiver specifies in the receive window field the amount of additional data, in
bytes, that it is willing to buffer.
sliding window: Answer: Suppose the receiver sends:
ACK = 1000 WINDOW = 500
This means two things.
ACK = 1000
This means:
I have received everything up to byte 999. The next byte I expect is byte 1000.
WINDOW = 500
This means:
I can receive 500 more bytes.
So the sender is allowed to send:
bytes 1000 to 1499
Because:
1000+500−1=14991000 + 500 - 1 = 14991000+500−1=1499
So:
ACK = 1000, WINDOW = 500
means:
You may send bytes 1000-1499.
APPHIA – Crafted with Care and Precision for Academic Excellence.
4
