Network+ - Lesson 5: Explaining IPv4 Addressing

What is the CIDR notation of 255.255.240.0?

/20

Convert the decimal value 72 into binary.

01001000

What is the binary version of 255.255.0.0

1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 . 00000000 . 00000000

If the network ID is 10.1.0.0/22, how many IP addresses are available for allocation to host interfaces?

1,022. With a 22-bit mask, from the 32-bit IP address, there are 10 bits left for host addressing (32-22). 2 to the power 10 (210) is 1,024. You then need to subtract two for the network and broadcast addresses, which cannot be assigned to host interfaces.

What is the value of each bit within IPv4 binary octet? (1 1 1 1 1 1 1 1)

128 64 32 16 8 4 2 1 1 1 1 1 1 1 1 1

Convert the binary value 11110010 to decimal.

242

How many bits is an IPv4 address?

32 bits or four 8-bit octets.

First octet range 1-126 is considered a class ___ address.

A

What is an ARP request?

A host sending a broadcast trying to obtain a physical address of another host i.e. "If this is your IP address what is your MAC address?"

What is a VLAN?

A logically separate network, created by using switching technology. Even though hosts on two VLANs may be physically connected to the same cabling, local traffic is isolated to each VLAN so they must use a router to communicate.

What is a network mask?

A mechanism that allows a network to divided IP addresses into network and host portions while also defining the network class.

What is a subnet mask?

A subnet mask is a mechanism that allows a network to divide IP addresses into a network, subnet and host portions.

What is ARP?

Address Resolution Protocol is a broadcast mechanism by which the hardware MAC address of an interface is matched to an IP address on a local network segment.

What type of addressing delivers a packet to a single host from a group without using unicast?

Anycast* means that a group of hosts are configured with the same IP address. When a router forwards a packet to an anycast group.

First octet range 128-191 is considered a class ___ address.

B

First octet range 192-223 is considered a class ___ address.

C

What is CIDR notation?

Classless Inter-Domain Routing is an alternate method of representing a subnet mask. It is simply a count of the number of network bits (bits that are set to 1) in the subnet mask. For example 255.255.0.0 can be expressed as /16

True or False. Forwarding at layer 3 is referred to as switching, while forwarding at layer 2 is described as routing.

False. Forwarding at layer 3 is routing*, while forwarding at layer 2 is switching*.

True or False. The first and last IP addresses in a subnet can be assigned to any host.

False. The first and last IP addresses in a subnet are reserved for the Network ID and broadcast address.

What is dotted decimal notation?

Format for expressing IPv4 addresses using four decimal values from 0 to 255 for each octet. Example: 10.10.10.10 or 192.168.0.1

What is IGMP used for?

Internet Group Management Protocol (IGMP) is a Layer 3 protocol that allows hosts to join and leave groups configured to receive multicast communications.

If all the bits in an octet are set to 1, the number obtained is 255 (the maximum possible value). Similarly, if all the bits are set to 0, the number obtained is 0 (the minimum possible value). Therefore, theoretically an IPv4 address may be any value between 0.0.0.0 and 255.255.255.255. However, some addresses are not permitted or are reserved for special use.

Just a note, no question.*

Network mask and Subnet mask are often used as if they're the same thing, but subnet masks are mostly used in network configurations, while netmasks often refer to classes of IP addresses. They're used to define a range of IP addresses that an ISP or other organization can use.

Just a note, no question.*

The purpose of subnetting is to create layer 3 broadcast domain segments with fewer hosts. The trick with subnet design is to fit the scheme to the requirements for number of subnetworks and number of hosts per subnet. Each bit added to the mask approximately halves the number of available host addresses.

Just a note, no question.*

When a packet is addressed to a selection of hosts (in IP, those belonging to a multicast group) is called?

Multicasting

What are the four most important IP addresses within a subnet?

Network ID (first address) Broadcast Address (Last address) First Host Last Host

Is the following string a valid network mask? 11111111 00000000 11111111 00000000

No, masks must be *contiguous* in order to separate the network and host portions of an IP address. Example of a valid mask: 11111111 11111111 11111111 00000000

What is the significances of 127.0.0.1?

That is the universal *Loopback Address* which is a special address typically used to check that TCP/IP is correctly installed on the local host.

When the destination IPv4 address is on a different IP network or subnet, the host forwards the packet to what?

The Default Gateway.

If a packet is addressed to a remote network, what destination MAC address will the sending node use to encapsulate the IP packet in a frame?

The MAC address of the default gateway.

True or False. Any number between 0 to 255 can be created by adding combinations of 128 64 32 16 8 4 2 1.

True

True or False. The binary expression of IPv4 is in base 2, digits can take one of two different values (0 and 1). The place values are powers of 2.

True.