TestOut Network+ 5.7

Broadcast

A single packet that, when sent, is processed by all hosts. Broadcast packets are not typically forwarded by routers, so broadcast traffic is limited to within a single subnet.

Which type of address is the IP address 198.162.12.254/24? A. Unicast B. Broadcast C. Multicast D. Private

A. Unicast The address 198.162.12.254 is a unicast address that identifies a single host on the 198.162.12.0 subnet. 198.162.12.255 is the broadcast address for the subnet. Multicast addresses are in the range of 224.0.0.0 to 239.255.255.255. The private IPv4 address ranges are: 10.0.0.1 to 10.255.255.254 172.16.0.1 to 172.31.255.254 192.168.0.1 to 192.168.255.254

IGMP (Internet Group Management Protocol)

IGMP is used to identify group members and to forward multicast packets on to the segments where group members reside.

IGMP Snooping on a switch

IGMP snooping on a switch allows the switch to control which ports get IGMP traffic for a specific group. With IGMP snooping, the switch identifies which ports include members of a specific multicast group. When a message is received for a group, the message is sent only to the ports that have a group member connected.

Unicast

Messages are sent to a specific host address. The sending device must know the IP address of all recipients and must create a separate packet for each destination device.

Multicasting

Multicasting creates logical groups of hosts—messages sent to the group are received by all group members. Multicasting is typically used for streaming video and audio applications, such as video conferencing.

IGMP routers keep track of the attached subnets that have group members:

1. A router sends out a host membership query. This query is addressed to the IP address 224.0.0.1. The address 224.0.0.1 is never assigned to a group because it is used for the query messages sent by routers. 2. Hosts that are members of any group respond with a list of the groups they belong to. Each group is identified with a multicast IP address in the range of 224.0.0.0 to 239.255.255.255. 3. The router uses these responses to compile a list of the groups on the subnet that have group members. Routers do not keep track of individual hosts that are members of a group; they simply compile a list of groups on the subnet that have at least one member. 4. When a host joins a new group, it automatically sends a join group message to the router. When the last host in a group leaves the group, it sends a leave group message to the router. 5. The IGMP router reports to upstream routers that they have members of a specific group. Upstream routers are the routers that exist between the router and the server that sends out the multicast data stream. They keep track of downstream routers that have group members.

Sending a Multicast stream

1. The sending server sends packets addressed to the multicast group. 2. Routers receive the multicast packets and check their lists of group members. If the router is connected to a subnet that has group members, or if the subnet includes a downstream router with group members, the multicast packet is sent on that subnet. If a subnet does not have any group members, the packet is not forwarded to that subnet. If a router does not have any subnets with group members, the packet is dropped and not forwarded. 3. Each intermediary router performs the same tasks until the data stream eventually reaches the multicast client.

A regular switch that receives Multicast traffic

A regular switch that receives multicast traffic sends the traffic out all ports, because the destination MAC address will be an unknown address. This means that a host might see multicast traffic on its segment, even if it isn't a member of the group. However, hosts that are not members of the group will not process the frame because they will not associate the multicast MAC address with their own address.

Which type of address is the IP address 232.111.255.250? A. Private B. Multicast C. Unicast D. Broadcast

B. Multicast The address 232.111.255.250 is a multicast address. A multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. Multicast addresses are in the range of 224.0.0.0 to 239.255.255.255. A unicast address is an address that identifies a single host. A broadcast address is an address that is sent to all hosts. Broadcast addresses are the last possible address on a subnet (typically ending in 255). The private IPv4 address ranges are: 10.0.0.1 to 10.255.255.254 172.16.0.1 to 172.31.255.254 192.168.0.1 to 192.168.255.254

Which address type is used for a video conference call consisting of multiple participants? A. Anycast B. Unicast C. Multicast D. Loopback

C. Multicast Unified communication (UC) systems typically use unicast network transmissions. An example of a unicast transmission is a one-on-one VoIP phone call. UC systems also support multicast transmissions. Examples of a multicast transmission are conference phone calls or video conference calls consisting of multiple users.

Which type of address is used in a packet to address the packet to a single host? A. Full-duplex B. Broadcast C. Unicast D. Multicast E. Simplex

C. Unicast A unicast address is an address that identifies a single host. A broadcast address is an address that is sent to all hosts. Broadcast traffic is typically only forwarded within (but not between) a subnet. A multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. Simplex communication uses a single channel for both sending and receiving. Full-duplex has a dedicated send and receive channel between any two hosts.

Which protocol does an IP host use to inform a router that it wants to receive specific multicast frames? A. SNMP B. IP C. ICMP D. IGMP E. MGP

D. IGMP IP hosts use the IGMP, or internet group management protocol, to inform multicast-enabled routers that they want to receive specific multicast frames.

Which of the following address types is shared by multiple hosts and used to form groups of computers that receive the same data stream? A. Unicast B. Broadcast C. Simplex D. Multicast E. Half-duplex

D. Multicast A multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. A unicast address is an address that identifies a single host. A broadcast address is an address that is sent to all hosts. Broadcast traffic is typically only forwarded within (but not between) a subnet. Simplex communication uses a single channel for both sending and receiving. Half-duplex uses a separate channel for sending and receiving, but the channels are shared by multiple devices and can only be used by a single device at a time.

Frames that contain Multicast traffic

Frames that contain multicast traffic are sent to a special MAC address. The MAC address begins with 01-00-5E, with the last portion being a form of the IP multicast group address. A single multicast MAC address could be shared by up to 5 other IP multicast addresses.