Knowledge Checks

What is the Internet Protocol?

What are the principal components of the IPv4 protocol (check all that apply)?

Routing algorithms and protocols like OSPF and BGP.

Packet handling conventions at routers (e.g., segmentation/reassembly)

ICMP (Internet Control Message Protocol)

SDN controller protocols.

IPv4 addressing conventions.

IPv4 datagram format.

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1/11

The IPv4 header.

Match each of the following fields in the IP header with its description, function or use.

Question List:

Version field

Type-of-service field

Fragmentation offset field

Time-to-live field

Header checksum field

Upper layer field

Payload/data field

Datagram length field.

Answer List:

The value in this field is decremented at each router; when it reaches zero, the packet must be dropped.
This field contains the IP protocol version number.
This field indicates the total number of bytes in datagram.
This field is used for datagram fragmentation/reassembly.
This field contains the Internet checksum of this datagram's header fields.
This field contains ECN and differentiated service bits.
This field contains a UDP or TCP segment, for example.
This field contains the "protocol number" for the transport-layer protocol to which this datagram's payload will be demultiplexed - UDP or TCP, for example.

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What is an IP address actually associated with?

Which of the following statements is true regarding an IP address? (Zero, one or more of the following statements is true).

An IP address is associated with an interface.

It is not necessary for a device using the IP protocol to actually have an IP address associated with it.

If a router has more than one interface, then it has more that one IP address at which it can be reached.

If a host has more than one interface, then it has more that one IP address at which it can be reached.

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What is a subnet?

What is meant by an IP subnet? (Check zero, one or more of the following characteristics of an IP subnet).

A set of devices all manufactured by the same equipment maker/vendor.

A set of devices that always have a common first 16 bits in their IP address.

A set of device interfaces that can physically reach each other without passing through an intervening router.

A set of devices that have a common set of leading high order bits in their IP address.

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4/11

Subnetting(a).

Consider the three subnets in the diagram below.

What is the maximum # of interfaces in the 223.1.2/24 network?

Two hosts, as shown in the figure.

256

2**32

128

There's no a priori limit on the number of interfaces in this subnet.

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5/11

Subnetting(b).

Consider the three subnets in the diagram below.

What is the maximum # of interfaces in the 223.1.3/29 network?

There's no a priori limit on the number of interfaces in this subnet.

2**32

Three hosts, as shown in the figure.

128

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6/11

Subnetting(c).

Consider the three subnets in the diagram below.

Which of the following addresses can not be used by an interface in the 223.1.3/29 network? Check all that apply.

223.1.3.2

223.1.3.16

223.1.2.6

223.1.3.28

223.1.3.6

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Plug-and-play.

What is meant by saying that DHCP is a "plug and play" protocol?

The network provides an Ethernet jack for a host’s Ethernet adapter.

No manual configuration is needed for the host to join the network.

The host needs to “plug” (by wire or wirelessly) into the local network in order to access (“play” in) the Internet

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8/11

DHCP request message.

Which of the following statements about a DHCP request message are true (check all that are true). Hint: check out Figure 4.24 in the 7th and 8th edition of our textbook.

A DHCP request message is optional in the DHCP protocol.

A DHCP request message is sent broadcast, using the 255.255.255.255 IP destination address.

A DHCP request message may contain the IP address that the client will use.

A DHCP request message is sent from a DHCP server to a DHCP client.

The transaction ID in a DCHP request message is used to associate this message with previous messages sent by this client.

The transaction ID in a DHCP request message will be used to associate this message with future DHCP messages sent from, or to, this client.

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9/11

IPv4 versus IPv6.

Which of the following fields occur ONLY in the IPv6 datagram header (i.e., appear in the IPv6 header but not in the IPv4 header)? Check all that apply.

The header length field.

128-bit source and destination IP addresses.

The flow label field.

The time-to-live (or hop limit) field.

The IP version number field.

The header checksum field.

The options field.

The upper layer protocol (or next header) field.

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10/11

Purpose of DHCP.

What is the purpose of the Dynamic Host Configuration Protocol?

To configure the set of available open ports (and hence well-known services) for a server.

To get the 48-bit link-layer MAC address associated with a network-layer IP address.

To obtain an IP address for a host attaching to an IP network.

To configure the interface speed to be used, for hardware like Ethernet, which can be used at different speeds.

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11/11

Knowledge checks

What is the Internet Protocol?

The IPv4 header.

Question List:

Answer List:

What is an IP address actually associated with?

What is a subnet?

Subnetting(a).

Subnetting(b).

Subnetting(c).

Plug-and-play.

DHCP request message.

IPv4 versus IPv6.

Purpose of DHCP.