sheet 3

About the TTL field in the IPv4 header, which is correct?

• When a route has a loop, the TTL value can be used to prevent the packet from being forwarded indefinitely.

• The TTL value is reduced by 1 for each Layer 3 device.

• The TTL value is 8 bits long.

• The range of TTL values is 0-255

Which of the following statements about the TTL field in the IP packet header is correct?

• Whenever a IP packet passes through a router, its TTL value is decremented by 1.

• Whenever a IP packet passes through a router, its TTL value will be increased by 1.

• TTL defines the time interval at which the source host can send packets.

• TTL defines the number of packets that the source host can send.

Which fields are not included in the network layer header format?

• TTL

• Source IPv4 Address

• Sequence Number

• Destination IPv4 Address

The last option field of IPv4 is variable length optional information. What is the maximum length of this field?

• 40B

• 20B

• 60B

• 10B

An IPv4 packet header length field is 20B, and the total length field is 1500B, then what is the packet payload?

• 20B

• 1520B

• 1480B

• 1500B

Which of the following is unlikely to be the IPv4 packet header length?

• 20B

• 64B

• 60B

• 32B

Which of the following IPv4 addresses is a Class A address?

• 100.1.1.1

• 172.16.1.1

• 127.1.1.1

• 192.168.1.1

Which field in the IPv4 header is used to prevent a packet from traversing a network endlessly?

• Time-to-Live

• Sequence Number

• Acknowledgment Number

• Differentiated Services

What IPv4 header field identifies the upper layer protocol carried in the packet?

• Protocol

• Identification

• Version

• Differentiated Services

Which term describes a field in the IPv4 packet header used to identify the next level protocol?

• protocol

• destination IPv4 address

• source IPv4 address

• TTL