CGS 4285 - Final Study Guide

Given the following forwarding table, determine the outgoing link interface for the destination address 11001000 00010111 00011000 10101010. Prefix Link Interface 11001000 00010111 00010. "0" 11001000 00010111 00011000. "1" 11001000 00010111 00011. "2" Otherwise. "3"

1

To use the traceroute command to measure the RTT (round trip time) between the source and the first router on the path, what should be the TTL (time to live) value in the UDP segment sent by traceroute?

1

Apply Dijkstra's algorithm to the network below using node e as the source. The algorithm will be initialized as follows: Since D(c) is the minimum among all the nodes not in N', c will be added to N'. After adding c to N', what will be the updated value for D(d)?

17

In the subnet 11.22.33.44/24 represented using the CIDR notation, how many IP addresses are available?

256

How many different keys does DES have?

2^(56)

Using a 4-bit generator, how many bits of transmission errors can be detected by CRC (cyclic redundancy check)?

3

Apply Dijkstra's algorithm to the network below using node a as the source. In the initialization step, what should be the distance from a to b D(b)?

30

How many IPv4 addresses are available in total approximately?

4 billion

Apply the distance vector algorithm to the network below. Assume that node a receives the following distance vector from node b: and the following distance vector from node d: After node a updates its distance vector, what is its distance to e?

60

What is the protocol to translate an IP address to a MAC address?

ARP

Which of the following is not true about hash functions?

It is impossible to find two inputs that will generate the same output.

What may be the motivation to set up a VLAN?

Lack of traffic isolation Managing users Inefficient use of switches

Without digital certificates to verifying the party identities, it is possible for Trudy (attacker) to intercept authentication packets between Alice and Bob, impersonating Bob to Alice and impersonating Alice to Bob. What is the name of this attack?

Man in the middle

What is the main function of the data plane of the network layer?

Move packets from router inputs to appropriate outputs

Which of the following devices can be implemented using OpenFlow?

NAT Router Firewall Switch

What are the three main approaches used to forward multicast datagrams?

Protocol Independent multicast Sparse Mode: This is a protocol that uses source-based trees or shared based. The host that needs to join the group sends the request to the root for joining. Protocol Independent Multicast Dense mode: This is an opt-out protocol, in which data is sent to all the hosts and the hosts that are not part ask for an opt-out from the tree. Distance Vector Multicast Routing: This is also a kind of opt-out protocol.

Identify the three categories of MAC protocols.

Random access Taking turns Channel partitioning

Consider the network shown below with four autonomous systems. Suppose AS3 and AS2 are running OSPF for their intra-AS routing protocol. Suppose AS1 and AS4 are running RIP for their intra-AS routing protocol. Suppose eBGP and iBGP are used for the inter-AS routing protocol. Identify the type of connection between router 3a and 1c.

eBGP

Which of the following is not a feature of RSA?

faster than symmetric key cryptography

When an Ethernet switch forwards a packet, if the destination MAC address is not in the switch table, the switch will do a _____; otherwise, if the destination MAC address is in the switch table, the switch will do a _____.

flood/broadcast selective send/selective forward

Multicast is one to _____ transmission. Broadcast is one to _____ transmission.

many/multiple all

For certain security sensitive network applications, the sender and receiver want to ensure messages not altered (in transit, or afterwards) without detection. What is the name of this security requirement?

message integrity

To prevent replay attacks, authentication protocols create a number that will be used only once. The number is called a _____.

nonce

Assume that a router interface receives two types of packets: multimedia and data. The multimedia packets are delay sensitive and the data packets are not. Therefore, the router interface transmits data packets only when there are not multimedia packets in the buffer. Which scheduling mechanism should be used?

priority scheduling

A digital certificate is a banding between a particular entity and its _____.

public key

Which of the following is not an advantage of SDN?

scalable routing

What are the service modes of wireless networks?

Ad-hoc mode Infrastructure mode

What is an autonomous system?

An autonomous system is a collection of networks under a common administration that share a routing strategy. These may be run by one or more operators.

Where is BGP used?

As the routing protocol that is used between different Internet Service Providers between the autonomous system. This is used to exchange the routing information between the various ISP.

What is the standard inter-AS routing protocol in today's Internet?

BGP

If a packet needs to be sent to every host in the network, which transmission mode should be used?

Broadcast

What is the MAC protocol used by 802.11 Wi-Fi?

CSMA/CA

With CDMA (Code Division Multiple Access), each user is assigned a different

Chipping sequence

Which of the following is not a service provided by the link layer?

Congestion control

Which protocol allows host to dynamically obtain its IP address when it joins network?

DHCP

In the abstraction of a network, routers are represented as vertices, and links are represented as edges. What might be the cost of a link in real life?

Delay Distance Available bandwidth

Select the header fields that can be used to define a pattern with OpenFlow.

Destination MAC address Destination port number Destination IP address

For the network below, A sends a packet to B. When the frame is transmitted between A and R, what is the destination MAC address?

E6-E9-00-17-BB-4B

CSMA (carrier sensing multiple access) completely eliminates collisions.

False

Datagram networks provide connection oriented service.

False

OSPF uses a distributed algorithm to calculate the routing tables. (Hint: OSPF is based on the link state algorithm.)

False

One dimensional parity checking can detect a 2-bit error.

False

In 4G cellular networks, both voice and data are carried on a common core based on _____.

IP

Identify the components for a router.

Input ports Switching fabric Output ports Routing processer

List and explain the two types of Internet routing protocols.

Interior Gateway Protocol and Exterior Gateway Protocols are the types of routing Protocols. Interior Gateway Protocols: These are the protocols that are used within the autonomous system. Protocols include RIP, OSPF. Exterior Gateway Protocols: These are the protocols that are used between autonomous systems. This is called as Inter-AS routing. Protocols include BGP.

The distance vector routing algorithm allows nodes to work asynchronously.

True

With DHCP, a host will receive not only an IP address but also the local DNS server information.

True

Select the features of Ethernet.

Unreliable Connectionless Using CSMA/CD as MAC protocol

Apply the distance vector algorithm to the network below. In the initialization step, what should be the distance from a to c da(c)?

a does not know the existence of c.

For the chosen-plaintext attack, the attacker can access

ciphertext corresponding to plaintext

Which of the following is not a reason for hierarchical routing?

To find shorter paths