CHAPTER 3:

Calculate the bandwidth-delay (in microseconds) when sending a 1000-byte packet

on a 1 Gbps link.
Answer: 8
Calculate the propagation delay (in microseconds) of a 10,000-meters-Fiber cable.
Note:

 Remove the numbers after the decimal point (e.g., 100.15 --> 100).

Answer: 50

What is the maximum Ethernet packet size of the IPv6 packet?

2000 bytes

CHAPTER 5

Can IPv6 subnet with the network prefix larger than 64 bits? Yes

How many bits for IPv6? 128

What parameters will be used in the secure hashing method to specify the IPv6
interface identification?

Net_Iface
Host-specific secret key
IPv6 address prefix

How many bytes for the default IPv6 header? 40

The IPv6 network prefix will be contained in message:

Router Advertisement
How IPv6 host can ask for the MAC address of the specific IPv6 address?
Neighbor Solicitation

Shorten the IPv6 following below:

1843:0F01:0000:0022:0000:0000:0000:00FA
Answer: 1843:F01:0:22::FA

Convert the MAC address of FC:99:47:75:CE:E0 to IPv6 host prefix (64 bits)
using EUI-64.

Note:

 Use ":" to separate the hextec and the capitalize character.

 Ex: FFFF:FFFF:FFFF:FFFF

Answer: FE99:47FF:FE75:CEE0

Does IPv6 have a header checksum? No

Which host address assignment option to ask for all IPv6 information from IPv6
DHCP? Option 1

CHAPTER 6

Assume that two hosts request the same service (e.g., DNS) from a server at the
same time. And then, the server returns two UDP packets to two that hosts.
How can the server know which packet belongs to which host? Based on the
source IP address.

Which model is currently used in the internet? TCP/IP

How many layers are in the OSI model? 7

How many fields are in the UDP header? 4

How many layers are in the TCP/IP model? 4

Assume that a host requests a service (e.g., DNS) from a server two times by two
different sessions of one application. And then, the server returns two UDP packets
to the host.
How can the host know which packet belongs to which session? Based on the
destination port.

Port 50000 is the: Private and/or Dynamic Ports

Can UDP re-order the reordering packet at the destination? No

Which one is characteristic of both UDP and IP protocols? Best-effort delivery

Assume that a host requests two services (DNS, TFTP) from a server at the same
time.
How can the server know which packet requests which service? Based on the
destination port.

CHAPTER 7
Assume that packet A was lost and retransmitted 4 times in a row. How long is it
between the first transmission and the last retransmission?

Note that:

 All settings are default.

 The TCP timeout value is 1 second.
 Skip all transmission delays (e.g., Bandwidth delay, propagation delay,
queuing delay, etc.)
Answer: 15

What type of TCP packet has the flag value of 18? SYN + ACK

With default options, how many ACK packets are sent by the sink when it receives
100th to 120th data packets?
Know that:

 No packet lost.
 When the sink received the 100th data packet, it did not return an ACK
packet.
 The last data packet arrived at the sink 500 ms ago.

Answer: 11

What characteristic below is wrong in TCP? Connectionless

How does MTU discovery work in the IPv4 network?

Answer: The network device sends sequential packets of different sizes with the
DF flag set.

How to disconnect the TCP connection immediately? Send RST packet

CHAPTER 8:

Internet is a: Congestion network.

How can the network device in the internet (e.g., router) decrease the pressure of
traffic from the end-host?
Answer: There is no method to do that.

How to decrease the pressure of traffic to avoid overload of the internet network?
Answer: TCP at end-host decreases the sending rate when congestion happens on
the internet.

How does the standard TCP sense the congestion happening? Packet loss happens.

[Multiple choices] How does the TCP define a packet loss?

Answer:
- The source received the three duplicate ACK packets.
- Timeout happens at the source.

In the Tahoe algorithm, when a packet loss is detected, the new congestion window
(cwnd) is set to: 1

In the NewReno algorithm, when a packet loss is detected, the new congestion
window (cwnd) is set to: cwndold/2

What is the difference between Reno and NewReno? Partial ACKs.

When does the TCP running NewReno algorithm retransmit the loss packet?
Answer: Right after receiving the duplicate ACK packets.

How many discrete lost packets can SACK detect? 3