Chapter 10
11. What is the network ID with CIDR notation for the IP address 172.16.32.108 with the subnet mask 255.255.255.0?
Answer: 172.16.32.0/24
16. Subnetting operates at Layer ___ while VLANs function at Layer ___.
Answer: 3; 2
14. What are four advantages to using virtualization on a network?
Answer: Efficient use of resources Cost and energy savings Fault and threat isolation Simple backups, recovery, and replication
17. Which VLAN on a switch manages untagged frames?
Answer: Native VLAN
19. Why is a BPDU filter needed at the demarc point?
Answer: The ISP's STP-related topology information shouldn't be mixed with a corporate network's STP-related topology information.
15. How does a vNIC get a MAC address?
Answer: Upon creation, each vNIC is automatically assigned a MAC address.
18. An attacker configures a VLAN frame with two tags instead of just one. The first tag directs the frame to the authorized VLAN. After the frame enters the first VLAN, the switch appropriately removes the tag, then discovers the next tag, and sends the frame along to a protected VLAN, which the attacker is not authorized to access. What kind of attack is this?
Answer: VLAN hopping
20. Only one ___________________ exists on a network using STP.
Answer: root bridge
7. Which protocol assigns a virtual IP to a group of routers? A. VTP B. VRRP C. SDN D. STP
B. VRRP
8. While designing your network's VLAN topology, your team has decided to use a centrally managed DHCP server rather than creating a separate DHCP server for each VLAN. What software will you need? A. DHCP server B. Hypervisor C. DHCP relay agent D. Subnet mask
C. DHCP relay agent
10. Telnet and SSH are called __________________ systems because they use the existing network and its protocols to interface with the switch. A. Virtual terminal B. Management console C. In-band management D. Switch port security
C. In-band management
6. With which network connection type does the VM obtain IP addressing information from its host? A. Bridged mode B. Managed mode C. NAT mode D. Host-only mode
C. NAT mode
3. Which of the following is not a good reason to subnet a network? A. To reduce the number of hosts on the same network B. To increase the number of unique networks available C. To reduce the number of routing table entries by combining several entries D. To segment a network
C. To reduce the number of routing table entries by combining several entries
5. What virtual, logically defined device operates at the Data Link layer to pass frames between nodes? A. Virtual bridge B. Virtual firewall C. Virtual switch D. Virtual router
C. Virtual switch
2. What is the formula for determining the number of possible hosts on a network? A. 2n = Y B. 2n - 2 = Y C. 2h = Z D. 2h - 2 = Z
D. 2h - 2 = Z
4. What is the software that allows you to define VMs and manage resource allocation and sharing among them? A. Host B. Guest C. Switch D. Hypervisor
D. Hypervisor
9. Which port on a switch manages traffic for multiple VLANs? A. Access port B. Console port C. Serial port D. Trunk port
D. Trunk port
1. How many bits of a Class A IP address are used for host information? a. 8 bits b. 16 bits c. 24 bits d. 32 bits
c. 24 bits
Virtualization
- For a single computer, virtualization can emulate the hardware, operating system, and or applications. For networking, virtualization can emulate hardware, including cabling and network devices, and software, including the network operating system and network management systems.
Troubleshooting VMs and VLANs
- In some cases for example, when it comes to backups, troubleshooting, and software updates- virtual network management is nearly identical to physical network management. However, an important different arises when managing virtual machines in VLANs. To create a VLAN, you modify a physical switch's configuration. However, to add VMs to a VLAN defined on a physical network, you use the hypervisor to modify a virtual switch's configuration.
Virtual Network Components
- When you create a VM, you use the virtualization program to assign the VM's software and hardware characteristics. These characteristics can differ completely from those of the host machine. - VMs can communicate with a virtual switch on the host computer to reach the physical network and, thereby, communicate with physical or virtual routers, other network devices, and other hosts on its own or another network. - A vNIC using bridged mode accesses a physical network using the host machines NIC and appears to other nodes as just another client or server connected directly to the network. - a vNIC using NAT mode relies on the host machine to act as a NAT device. - In host-only mode, VMs on one host can exchange data with each other and with their host, but they cannot communicate with any nodes beyond the host. -Sometimes virtual services and devices are implemented for the purpose of redundancy. In the case of routers, VRRP or HSRP is used to assign a virtual IP address to a group of virtual routers. - In software defined networking (SDN), services are delivered by applications that are managed by a network controller, which also integrates all of the network's virtual and physical devices into one cohesive system.
VLANs and Trunking
-Programmable switches create VLANs by partitioning their ports into groups. In most situations, each VLAN is assigned its own subnet of IP addresses, so that a layer 3 subnet includes the same group of hosts as does the layer 2 VLAN. -Switches and bridges use STP (spanning tree protocol) to help eliminate the possibility of broadcast storms and other types of traffic loops. - An unmanaged switch provides plug-and-play simplicity with minimal configuration options and has no IP address assigned to it. Managed switches, on the other hand, can be configured via command line interface and sometimes can be configured in groups. -A large wireless network is often managed by a central wireless controller, which provides a central management console for all the APs in a network.
Segmentation and subnetting
-Separating traffic by subnets or VLANs helps enhance security, improve network performance, and simplify troubleshooting. - Adhering to the classful addressing model limits flexibility in determining the number of possible hosts in a single network. -CIDR notation takes the network ID or a host's IP address and follows it with a forward slash, followed by the number of bits that are used for the network ID. - To create a subnet, you must borrow bits that would represent host information in classful addressing and use those bits instead to represent network information. - Each network class reserves a different number of bits for network information and a different number of bits for host information. Therefore, the number of possible hosts and subnets on a network will vary depending on your network class and the way you implement subnets. - Supernetting allows you to combine contiguous networks that all use the same CIDR block into one supernet. -To calculate a host's network ID given its IPv4 address and subnet mask, you can follow a logical process of combining bits known as ANDing. - Subnetting in IPv6 is simpler than subnetting in IPv4. One substantial difference is that unlike IPv4 addressing, IPv6 addressing does not use class information when subnetting.
