Chapter 11: IPv4 Addressing
What is the prefix length notation for the subnet mask 255.255.255.224? /25 /28 . /26 /27
/27
What is the range and prefix of classful A?
0.0.0.0 - 127.0.0.0 /8
IPv4 unicast host addresses are in the address range of what?
1.1.1.1 - 223.255.255.255 However, within this range are many addresses that are reserved for special purposes. These special purpose addresses will be discussed later in this module.
What is the private address range and prefix for class A network?
10.0.0.0 - 10.255.255.255 /8
What is the network if for the Loopback address and slash notation?
127.0.0.0 /8
What is the range for the Class A loopback?
127.0.0.1 - 127.255.255.254
What is the range and prefix of classful B?
128.0.0.0 - 191.255.0.0 /16
If a network device has a mask of /28, how many IP addresses are available for hosts on this network? 256 254 14 32 62 16
14
What is the Network ID for IPv4 link local addresses and slash notation?
169.254.0.0 /16
What is the host range for the IPv4 Link Local address?
169.254.1 - 169.254.255.254 /16
What is the private address range and prefix for class B network?
172.16.0.0 - 172.31.255.255 /12
What is the range and prefix of classful C ?
192.0.0.0 - 223.255.255.0 /24
What is the private address range and prefix for class C network?
192.168.0.0 - 192.168.255.255 /16
What IPv4 addresses are reserved for IPv4 multicast?
224.0.0.0 - 239.255.255.255
What is the reserved OSPF multicast address?
224.0.0.5
What subnet mask is represented by the slash notation /20? 255.255.240.0 255.255.255.0 255.255.224.0 255.255.255.192 255.255.255.248
255.255.240.0
Which subnet mask would be used if 5 host bits are available? 255.255.255.224 255.255.255.128 255.255.255.240 255.255.255.0
255.255.255.224
Which subnet mask would be used if exactly 4 host bits are available? 255.255.255.128 255.255.255.224 255.255.255.248 255.255.255.240
255.255.255.240
A network administrator is variably subnetting a network. The smallest subnet has a mask of 255.255.255.224. How many usable host addresses will this subnet provide? 2 30 62 6 14
30
How many usable IP addresses are available on the 192.168.1.0/27 network? 32 16 256 254 62 30
30
A network administrator subnets the 192.168.10.0/24 network into subnets with /26 masks. How many equal-sized subnets are created? 8 64 16 2 1 4
4
How many valid host addresses are available on an IPv4 subnet that is configured with a /26 mask? 64 62 190 254
62
If a network device has a mask of /26, how many IP addresses are available for hosts on this network? 64 62 16 30 32 14
62
What is a DMZ network?
A DMZ network is a public network which uses public IP addresses separate from an organization private network. It hoses public websites and other public resources. The end goal of a DMZ is to allow an organization to access untrusted networks, such as the internet, while ensuring its private network or LAN remains secure. Organizations typically store external-facing services and resources, as well as servers for the Domain Name System (DNS), File Transfer Protocol (FTP), mail, proxy, Voice over Internet Protocol (VoIP), and web servers, in the DMZ.
How do Ip directed broadcast work?
A device that is not directly connected to the destination network forwards an IP directed broadcast in the same way it would forward unicast IP packets destined to a host on that network. When a directed broadcast packet reaches a router that is directly connected to the destination network, that packet is broadcast on the destination network.
What is the problem with large broadcast domains?
A problem with large broadcast domains is that theses hosts can generate excessive broadcasts and negatively affect the network.
The actual process used to identify the network portion and host portion is called what?
ANDing
What are the two protocols that use destination broadcasts to obtain information needed for destination MAC address associated with a known IPv4 address or an IP address as well as a default gateway?
ARP or Address Resolution Protocol DHCP or Dynamic Host Configuration Protocol
Internet Control Message Protocol Version 6 can perform what two functions?
Address resolution Address autoconfiguration
What does dual stack migration technique allow on the network segment?
Allows IPv4 and IPv6 to coexist on the same network segment. Dual Stack devices run both IPv4 and IPv6 protocol stacks simultaneously.
What does NAT64 do?
Allows Ipv6-enabled devices to communicate with IPv4-enabled devices using translation technique similar to NAT for IPv4. An IPv6 packet is translated to an IPv4 packet and an IPv4 packet is translated to an IPv6 packet.
The last address in a range is known as what?
Broadcast Address is used to send information to all devices in the network and cannot be assigned to any host
Designed to support extremely large networks with more than 16 million host addresses.
Class A
Designed to support the needs of moderate to large size networks with up to approximately 65,000 host addresses.
Class B
Designed to support small networks with a maximum of 254 hosts.
Class C
Why is NAT problematic for many applications?
Creates latency Has Limitations that severely impede peer-topeer0 communications.
This is part of the company's network containing resources available to the internet such as a web server. Devices in the DMZ use public IPv4 addresses
DMZ
What is a DMZ stand for?
Demilitarized zone
What type of broadcast is used to send a broadcast packet to a remote net work so that all host that are apart of that network segment receive the process the packet?
Directed Broadcast
Which broadcast is sent to all hosts on a specific network? For example, a host on the 172.16.4.0/24 network sends a packet to 172.16.4.255
Directed Broadcast
The IETF has created various protocols and tools to help network administrators migrate their networks to IPv6. The migration techniques can be divided into three categories:
Dual Stack Tunneling Translation
A host typically acquires its IPv4 address configuration using what Layer 7 protcol?
Dynamic Host Configuration Protocol
Each multicast group is represented by what?
Each multicast group is represented by a single IPv4 multicast destination address. When an IPv4 host subscribes to a multicast group, the host processes packets addressed to this multicast address, and packets addressed to its uniquely allocated unicast address.
Most networks allocate IPv4 addresses to client devices dynamically, using Dynamic Host Configuration Protocol (DHCP). This reduces the burden on the network support staff and virtually eliminates entry errors. With DHCP, addresses are only leased for period of time, and can be reused when the lease expires. This is an important feature for networks that support transient users and warless devices. Changing the subnetting scheme means that the DHCP server needs to reconfigured, and the clients must renew their IPv4 addresses. IPv6 clients can obtain address information using DHCPv6 or SLACC.
End user clients
Within a network, there are different types of devices that require addresses:
End user clients Servers and peripherals Servers that are accessible from the internet Intermediary devices Gateway
Routers and firewall devices have an IP address assigned to each interface which serves as the gateway for the hosts in that network. Typically, the router interface uses either the lowest or highest address in the network.
Gateway
What are host addresses?
Host addresses are addresses that can be assigned to a device such as a host computer, laptop, smart phone, web camera, printer, router, etc. The host portion of the address is the bits indicated by 0 bits in the subnet mask. Host addresses can have any combination of bits in the host portion except for all 0 bits (this would be a network address) or all 1 bits (this would be a broadcast address).
Which IP protocols uses broadcast addresses?
IPv4 there are no broadcast packets with IPv6
Which IP protocol does not use broadcast packets?
IPv6
Packets with a private IPv4 address will filtered (discarded) or translated by what router?
ISP router
Why do you need a Default Gateway IPv4 address?
If you want to remote networks you need a default gateway.
Why does a device need to know what network it belongs to?
In order to forward data correctly
Why do you need a DNS server IPv4 address?
In order to translate domain names to IPv4 because computers only talk in binary.
These devices are assigned addresses for network management, monitoring, and security. Because we must know how to communicate with intermediary devices, they should have predictable, statically assigned addresses.
Intermediary Devices
What organization manages both IPv4 and IPv6?
Internet Assigned Numbers Authority (IANA)
This is the internal part of a company's network, accessible by only within the organization. Devices in the intranet use private IPv4 address.
Intranet
A enterprise network consists of what two types of networks?
Intranet (Internal Network) DMZ (Extranet)
What is loopback used for?
It can be used on a host to test if the TCP/IP configuration is operational and to direct traffic to itself
What are two major issues that can be caused by large broadcast domains?
It can result in slow network operation due to the significant amount of traffic it can cause, and slow device operations because a device must accept and process each broadcast packet.
How does subnetting help an administrator to implement security policies?
It enables an administrator to implement security policies such as which subnets are allowed or not allowed to communicate together.
A network address is an address that represents a specific network. A device belongs to this network if it meets three criteria:
It has the same subnet mask as the network address It has the same network bits as the network bits as the network address, as indicated by the subnet mask It is located on the same broadcast domain as other hosts with the same network address
What is a subnet mask?
It is used to identify the network/host portion of the IPv4 address
What is prefix length written in ?
It is written in slash notation, which is noted by a forward slash / followed by the number of bits set to 1.
Before the ISP can forward a packet with a packet IPv4 address, it must do what first?
It must translate the source IPv4 address, which is a private address, to a public Ip4 address using Network Address Translation (NAT)
Which type of broadcast is associated with 255.255.255.255 address and is used for the local network segment?
Limited Broadcast
What are the two different addresses that can be used to broadcast a packet on a local network?
Limited broad cast 255.255.255.255 Directed broadcast this will be the last address on the network segment
What are the three various ways of using subnets to help manage network devices?
Location Group or Function Device Type
What can cause abnormal broadcast traffic that will negatively affect the network?
Misconfigurations Hardware/Software problems Malicious intent
IPv4 Link-local address are also known as what?
More commonly known as the Automatic Private IP Addressing (APIPA) or self assigned addresses.
What are hosts called that receive particular multicast packets?
Multicast clients
How does multicast transmission help with traffic on the network?
Multicast transmission reduces traffic by allowing a host to send a single packet to a selected set of hosts that subscribe to a multicast group.
Routing protocols such as OSPF use what type of transmissions?
Multicast transmissions
The bits within the network portion of the address must be what for all devices that reside in the same network?
Must be identical for all devices that reside in the same network.
What is NAT used for?
NAT is used to translate between private IPv4 and public IPv4 addresses.
What does NAT64 stand for?
Network Address Translation 64
The first address in a range is known as what?
Network Address and cannot be assigned to any host
What are the three types of adderssses within each network?
Network address Host address Broadcast Address
An IPv4 address is a 32-bit hierarchical address that is made up of what two parts?
Network portion and Host portion
If a switch receives a broadcast will it propagate out all interfaces?
No, Switches propagate broadcasts out all interfaces except the interface on which it was received. For example, if a switch in the figure were to receive a broadcast, it would forward it to the other switches and other users connected in the network.
Will a router propagate a broadcast?
No, routers do not propagate broadcasts. When a router receives a broadcast, it does not forward it other interfaces.
What devices will be able to process OSPF packets with the destination multicast address of 224.0.0.5?
Only devices enabled with OSPF will process theses packets with 224.0.0.5 as the destination IPv4 address. All other devices will ignore these packets
What IPv4 addresses are used as internal hosts for an organization?
Private IPv4 addresses
What type of Ipv4 address are not unique and can be used internally within any network?
Private IPv4 addresses
Which two statements are correct about private IPv4 addresses? (Choose two.) Private IPv4 addresses are assigned to devices within an organization's intranet (internal network) Internet routers will typically forward any packet with a destination address that is a private IPv4 address. 172.99.1.1 is a private IPv4 address Any organization (home, school, office, company) can use the 10.0.0.0/8 address
Private IPv4 addresses are assigned to devices within an organization's intranet (internal network) Any organization (home, school, office, company) can use the 10.0.0.0/8 address
What IPv4 addresses are addresses which are globally routed between internet service provider (ISP) routers?
Public IPv4 addresses
Which organization or group of organizations receives IP addresses from IANA and is responsible for allocating these addresses to ISPs and some organizations? IETF IEEE RIRs Tier 1 ISPs
RIRs
RIRs are responsible for what?
RIRs are responsible for allocation IP address to ISP who provide IPv4 address blocks to organizations and smaller ISPs
The IANA manages and allocates blocks of IP addresses to who?
Regional Internet Registries (RIRs)
Which devices will not forward an IPv4 broadcast packet by default? Ethernet Switch Router Windows PC None of the above. All devices forward IPv4 broadcast packets by default.
Router
These should have a predictable static IP address. Use a consistent numbering system for theses devices.
Servers and Peripherals
Serves that need to be publicly available on the internet must have a public IPv4 address, most often accessed using NAT. In some organizations, internal servers (not publicly available) must be made available to remote users. In most cases, theses servers are assigned private addresses internally, and the user is required to create a virtual private network (VPN) connection to access the server. This has the same effect as if the user is accessing the server form a host within the intranet.
Servers that are accessible form the internet
Which two situations are the results of excessive broadcast traffic? (Choose two) Slow network operations Slow device operations When devices on all adjacent networks are affected When the router has to forward an excessive number of packets
Slow network operations Slow device operations
What are the smaller networks created subnetting a large broadcast domain called?
Subnets
The process of shrinking large broadcast domains is known as what?
Subnetting
What are some reasons to why you would want to create subnets?
Subnetting reduces overall network traffic Improves network performance Enables an administrator to implement security policies Reduces the number of devices affected by abnormal broadcast traffic
Why must the host portion of an IPv4 address be unique?
The bits within the host portion of the address must be unique to identify a specific host within a network.
What is the address after the network address called?
The fist usable address used for host
What is the address before the broadcast address called?
The last usable address used for host
Multicast clients use what to subscribe to a multicast group?
The multicast clients use services requested by a client program
What is a prefix length?
The prefix length is the number of bits set to 1 in the subnet mask.
Which statement is true about variable-length subnet masking? Bits are returned, rather than borrowed, to create additional subnets Subnets may only be subnetted on additional time. Each subnet is the same size The size of each subnet may be different, depending on requirements
The size of each subnet may be different, depending on requirements
What is the solution to large broadcast domains and the problems they cause?
The solution is to reduce the size of the network to create smaller broadcast domains in a process call subnetting.
What is a broadcast domain?
Therefore, each router interface connects to a broadcast domain and broadcasts are only propagated within that specific broadcast domain.
What operating system uses APIPA?
They are used by a Windows DHCP client to self configure in the event that there are no DHCP server available.
Which router handles NAT on a internal network?
This is usually done on the router that connects the internal network to the IPS network.
What does native IPv6 mean?
This means the customer network has an IPv6 connection to their ISP and is able to access content found on the internet over IPv6.
Which two statements are correct about public IPv4 addresses? (Choose two.) Public IPv4 addresses are allowed to be assigned to devices within an organization's intranet (internal network) To access a device over the internet, the destination IPv4 address must be a public address. 192.168.1.10 is a public IPv4 address Public IPv4 address exhaustion is a reason why there are private IPv4 address and why organizations are transitioning to IPv6
To access a device over the internet, the destination IPv4 address must be a public address. Public IPv4 address exhaustion is a reason why there are private IPv4 address and why organizations are transitioning to IPv6
How does the ANDing process work?
To do this, devices compare their host IP and their subnet mask bit-for-bit If the nit values are both a binary 1, the result is a binary 1 If one of the or both of the bit values is 0, the result is a binary 0
True or False: 4 out of 5 RIRs no longer have enough IPv4 addresses to allocate to customers on a regular basis. True False
True
True or False: All devices within the same network, must have the same subnet mask and the same network bits. Only the host bits will differ and must be unique.
True
True or False: Directed broadcast are turned off by default starting with cisco IOS Release 12.0.
True, because of security concerns and prior abuse from malicious users.
True or False: Private addresses are not globally routable
True, most internal networks, from large enterprises to home networks, use private IPv4 addresses for addressing all internal devices (intranet) including hosts and routers.
What is tunneling?
Tunneling is a method of transporting an IPv6 packet over an IPv4 network. The ipv6 packet is encapsulated inside an IPv4 packet similar to other types of data.
How does a device find the network it belongs to?
Using their host IP address, their subnet mask, and a process called binary ANDing, a device can find the network that it belongs to.
What is the most important motivating factor for moving to IPv6? better performance with IPv6 IPv6 addresses that are easier to work with better security with IPv6 depletion of IPv4 addresses
depletion of IPv4 addresses
Which of the following techniques use native IPv6 connectivity? dual stack tunneling translation all of the above
dual stack
What does the IP address 172.17.4.250/24 represent? network address host address broadcast address multicast address
host address
Which two parts are components of an IPv4 address? ( Choose two) network portion host portion logical portion broadcast portion physical portion subnet portion
network portion host portion
What command is used to turn off IP directed broadcast on cisco router?
no ip directed-broadcast
What command is used to test loopback on a device?
ping 127.0.0.1
What is the purpose of the subnet mask in conjunction with an IP address? to uniquely identify a host on network to mask the IP address to outsiders to identify whether the address is public or private to determine the subnet to which the host belongs
to determine the subnet to which the host belongs
Why does a layer 3 device perform the ANDing process on a destination IP address and subnet mask? to identify the host address of the destination host to identify the broadcast address of the destination network to identify faulty frames to identify the network address of the destination network
to identify the network address of the destination network
