How many valid host addresses are available on an IPv4 subnet that is configured with a slash 28 mask?
Taking an example IP address of 192.168.86.42, and a subnet mask of 255.255.255.0 (a /24 subnet), let's manually calculate the network and IP properties for this IP address. Show
IP typeCheck if the IP address is within any of the ranges of private IP addresses. If it is, then it is a private address. Otherwise, it is a public address. Looking at the ranges, we see that 192.168.86.42 is in the range 192.168.0.0 – 192.168.255.255 - a private address. IP classLooking through the ranges of each class in the previous section, we see that the IP address 192.168.86.42 is in the range 192.0.0.0 - 223.255.255.255, so it is a Class C IP address. Network addressLet's go through the calculation of the network address, step-by-step.
So, 192.168.86.0 is the network address. Total number of addressesNext, we'll calculate the total number of addresses, as we need that to work out the broadcast address. Use the equation for the total number of addresses, given that the CIDR is 24.
So, the total number of addresses is 256. Broadcast addressNow, we can calculate the broadcast address. Convert the network address from binary to decimal, which gives 3,232,257,536. Add 256 - 1 to get 3,232,257,791. Then convert this back to binary, separate it into 8-bit blocks, and convert to decimal. 3,232,257,791 So, the broadcast address for our example is 192.168.86.255. First and last host addressesFor the first usable host address, we add one to the network address. While you can do all of the converting to a decimal number, adding one, and switching back to the quad-dotted decimal format, usually, it's easy to work directly with the quad-dotted decimal. Adding one to the network address 192.168.86.0 is simply a matter of adding one to the last octet. Therefore it's 192.168.86.1 for the first usable host address. The same can be said when calculating the last usable host address, which is the broadcast address minus one. That gives a result of 192.168.86.254. Wildcard maskTo calculate the wildcard mask, convert the subnet mask to binary and flip all the bits. Then switch back to the quad-dotted decimal format.
The wildcard mask for our example is 0.0.0.255. IP address in integer and hexadecimalUsing the binary form of the IP address, we can convert the binary number to integer (base 10) and hexadecimal (base 16).
in-addr.arpaReverse the example IP address 192.168.86.42 to get 42.86.168.192 and put it in front of in-addr.arpa to get 42.86.168.192.in-addr.arpa. IPv4-mapped IPv6 addressIPv4-mapped IPv6 addresses consist of the prefix ::ffff: followed by the IPv4 address, either displayed in hexadecimal (IPv6 native) format or the IPv4 quad-dotted decimal format. The results for our example IP address is:
6to4 prefixThe 6to4 prefix consists of 2002: followed by the IP address in hexadecimal format. You can convert each octet to hexadecimal individually and write them out in the IPv6 form.
That's a lot of work here, isn't it? Thanks to our IP address subnet calculator, you can obtain all of this information in a minute! CCNA 1 v7.0 Modules 11 – 13: IP Addressing Exam Answers 20201. What is the prefix length notation for the subnet mask 255.255.255.224?/25 Explanation: The binary format for 255.255.255.224 is 11111111.11111111.11111111.11100000. The prefix length is the number of consecutive 1s in the subnet mask. Therefore, the prefix length is /27. 2. How many valid host addresses are available on an IPv4 subnet that is configured with a /26 mask?254 3. Which subnet mask would be used if 5 host bits are available?255.255.255.0 4. A network administrator subnets the 192.168.10.0/24 network into subnets with /26 masks. How many equal-sized subnets are created?1 5. Match the subnetwork to a host address that would be included within the subnetwork. (Not all options are used.)6. An administrator wants to create four subnetworks from the network address 192.168.1.0/24. What is the network address and subnet mask of the second useable subnet?subnetwork 192.168.1.64 subnetwork 192.168.1.32 subnetwork 192.168.1.64 subnetwork 192.168.1.128 subnetwork 192.168.1.8 7. How many bits must be borrowed from the host portion of an address to accommodate a router with five connected networks?two Explanation: Each network that is directly connected to an interface on a router requires its own subnet. The formula 2n, where n is the number of bits borrowed, is used to calculate the available number of subnets when borrowing a specific number of bits. 8. How many host addresses are available on the 192.168.10.128/26 network?30 Explanation: A /26 prefix gives 6 host bits, which provides a total of 64 addresses, because 26 = 64. Subtracting the network and broadcast addresses leaves 62 usable host addresses. 9. How many host addresses are available on the network 172.16.128.0 with a subnet mask of 255.255.252.0?510 Explanation: A mask of 255.255.252.0 is equal to a prefix of /22. A /22 prefix provides 22 bits for the network portion and leaves 10 bits for the host portion. The 10 bits in the host portion will provide 1022 usable IP addresses (210 – 2 = 1022). 10. Match each IPv4 address to the appropriate address category. (Not all options are used.)11. What three blocks of addresses are defined by RFC 1918 for private network use? (Choose three.)10.0.0.0/8* Explanation: RFC 1918, Address Allocation for Private Internets, defines three blocks of IPv4 address for private networks that should not be routable on the public Internet. 12. Refer to the exhibit.An administrator must send a message to everyone on the router A network. What is the broadcast address for network 172.16.16.0/22?172.16.16.255 Explanation: The 172.16.16.0/22 network has 22 bits in the network portion and 10 bits in the host portion. Converting the network address to binary yields a subnet mask of 255.255.252.0. The range of addresses in this network will end with the last address available before 172.16.20.0. Valid host addresses for this network range from 172.16.16.1-172.16.19.254, making 172.16.19.255 the broadcast address. 13. A site administrator has been told that a particular network at the site must accommodate 126 hosts. Which subnet mask would be used that contains the required number of host bits?255.255.255.0 Explanation: The subnet mask of 255.255.255.0 has 8 host bits. The mask of 255.255.255.128 results in 7 host bits. The mask of 255.255.255.224 has 5 host bits. Finally, 255.255.255.240 represents 4 host bits. 14. Refer to the exhibit.Considering the addresses already used and having to remain within the 10.16.10.0/24 network range, which subnet address could be assigned to the network containing 25 hosts?10.16.10.160/26 Explanation: Addresses 10.16.10.0 through 10.16.10.63 are taken for the leftmost network. Addresses 10.16.10.192 through 10.16.10.207 are used by the center network.The address space from 208-255 assumes a /28 mask, which does not allow enough host bits to accommodate 25 host addresses.The address ranges that are available include 10.16.10.64/26 and10.16.10.128/26. To accommodate
25 hosts, 5 host bits are needed, so a /27 mask is necessary. Four possible /27 subnets could be created from the available addresses between 10.16.10.64 and 10.16.10.191: 15. What is the usable number of host IP addresses on a network that has a /26 mask?256 Explanation: A /26 mask is the same as 255.255.255.192. The mask leaves 6 host bits. With 6 host bits, 64 IP addresses are possible. One address represents the subnet number and one address represents the broadcast address, which means that 62 addresses can then be used to assign to network devices. 16. Which address prefix range is reserved for IPv4 multicast?240.0.0.0 – 254.255.255.255 17. Refer to the exhibit.Match the network with the correct IP address and prefix that will satisfy the usable host addressing requirements for each network.Explanation: Network A needs to use 192.168.0.128 /25, which yields 128 host addresses. 18. A high school in New York (school A) is using videoconferencing technology to establish student interactions with another high school (school B) in Russia. The videoconferencing is conducted between two end devices through the Internet. The network administrator of school A configures the end device with the IP address 209.165.201.10. The administrator sends a request for the IP address for the end device in school B and the response is 192.168.25.10. Neither school is using a VPN. The administrator knows immediately that this IP will not work. Why?This is a loopback address. 19. Which three addresses are valid public addresses? (Choose three.)198.133.219.17* Explanation: The ranges of private IPv4 addresses are as folllows: 20. A message is sent to all hosts on a remote network. Which type of message is it?limited broadcast Explanation: A directed broadcast is a message sent to all hosts on a specific network. It is useful for sending a broadcast to all hosts on a nonlocal network. A multicast message is a message sent to a selected group of hosts that are part of a subscribing multicast group. A limited broadcast is used for a communication that is limited to the hosts on the local network. A unicast message is a message sent from one host to another. 21. A company has a network address of 192.168.1.64 with a subnet mask of 255.255.255.192. The company wants to create two subnetworks that would contain 10 hosts and 18 hosts respectively. Which two networks would achieve that? (Choose two.)192.168.1.16/28 22. Which address is a valid IPv6 link-local unicast address?FEC8:1::FFFF Explanation: IPv6 LLAs are in the fe80::/10 range. The /10 indicates that the first 10 bits are 1111 1110 10xx xxxx. The first hextet has a range of 1111 1110 1000 0000 (fe80) to 1111 1110 1011 1111 (febf). 23. Which of these addresses is the shortest abbreviation for the IP address: 3FFE:1044:0000:0000:00AB:0000:0000:0057?3FFE:1044::AB::57 Explanation: The rules for reducing the notation of IPv6 addresses are: 24. A network administrator has received the IPv6 prefix 2001:DB8::/48 for subnetting. Assuming the administrator does not subnet into the interface ID portion of the address space, how many subnets can the administrator create from the /48 prefix?16 Explanation: With a network prefix of 48, there will be 16 bits available for subnetting because the interface ID starts at bit 64. Sixteen bits will yield 65536 subnets. 25. Given IPv6 address prefix 2001:db8::/48, what will be the last subnet that is created if the subnet prefix is changed to /52?2001:db8:0:f00::/52 Explanation: Prefix 2001:db8::/48 has 48 network bits. If we subnet to a /52, we are moving the network boundary four bits to the right and creating 16 subnets. The first subnet is 2001:db8::/52 the last subnet is 2001:db8:0:f000::/52. 26. Consider the following range of addresses:2001:0DB8:BC15:00A0:0000:: Explanation: All the addresses have the part 2001:0DB8:BC15:00A in common. Each number or letter in the address represents 4 bits, so the prefix-length is /60. 27. What type of IPv6 address is FE80::1?loopback 28. Refer to the exhibit.A company is deploying an IPv6 addressing scheme for its network. The company design document indicates that the subnet portion of the IPv6 addresses is used for the new hierarchical network design, with the site subsection to represent multiple geographical sites of the company, the sub-site section to represent multiple campuses at each site, and the subnet section to indicate each network segment separated by routers. With such a scheme, what is the maximum number of subnets achieved per sub-site?0 Explanation: Because only one hexadecimal character is used to represent the subnet, that one character can represent 16 different values 0 through F. 29. What is used in the EUI-64 process to create an IPv6 interface ID on an IPv6 enabled interface?the MAC address of the IPv6 enabled interface* Explanation: The EUI-64 process uses the MAC address of an interface to construct an interface ID (IID). Because the MAC address is only 48 bits in length, 16 additional bits (FF:FE) must be added to the MAC address to create the full 64-bit interface ID. 30. What is the prefix for the host address 2001:DB8:BC15:A:12AB::1/64?2001:DB8:BC15 31. An IPv6 enabled device sends a data packet with the destination address of FF02::1. What is the target of this packet?the one IPv6 device on the link that has been uniquely
configured with this address 32. Match the IPv6 address with the IPv6 address type. (Not all options are used.)Explanation: FF02::1:FFAE:F85F
is a solicited node multicast address. 33. Which IPv6 prefix is reserved for communication between devices on the same link?FC00::/7 Explanation: IPv6 link-local unicast addresses are in the FE80::/10 prefix range and are not routable. They are used only for communications between devices on the same link. 34. Which type of IPv6 address refers to any unicast address that is assigned to multiple hosts?unique local 35. What are two types of IPv6 unicast addresses? (Choose two.)multicast Explanation: Multicast, anycast, and unicast are types of IPv6 addresses. There is no broadcast address in IPv6. Loopback and link-local are specific types of unicast addresses. 36. Which service provides dynamic global IPv6 addressing to end devices without using a server that keeps a record of available IPv6 addresses?stateful
DHCPv6 Explanation: Using stateless address autoconfiguration (SLAAC), a PC can solicit a router and receive the prefix length of the network. From this information the PC can then create its own IPv6 global unicast address. 37. Which protocol supports Stateless Address Autoconfiguration (SLAAC) for dynamic assignment of IPv6 addresses to a host?ARPv6 Explanation: SLAAC uses ICMPv6 messages when dynamically assigning an IPv6 address to a host. DHCPv6 is an alternate method of assigning an IPv6 addresses to a host. ARPv6 does not exist. Neighbor Discovery Protocol (NDP) provides the functionality of ARP for IPv6 networks. UDP is the transport layer protocol used by DHCPv6. 38. Three methods allow IPv6 and IPv4 to co-exist. Match each method with its description. (Not all options are used.)39. A technician uses the ping 127.0.0.1 command. What is the technician testing?the TCP/IP stack on a network host* 40. Refer to the exhibit.An administrator is trying to troubleshoot connectivity between PC1 and PC2 and uses the tracert command from PC1 to do it. Based on the displayed output, where should the administrator begin troubleshooting?PC2 41. Which protocol is used by the traceroute command to send and receive echo-requests and echo-replies?SNMP Explanation: Traceroute uses the ICMP (Internet Control Message Protocol) to send and receive echo-request and echo-reply messages. 42. Which ICMPv6 message is sent when the IPv6 hop limit field of a packet is decremented to zero and the packet cannot be forwarded?network unreachable 43. A user executes a traceroute over IPv6. At what point would a router in the path to the destination device drop the packet?when the value of the Hop Limit field reaches 255 44. What is the purpose of ICMP messages?to inform routers about network topology changes Explanation: The purpose of ICMP messages is to provide feedback about issues that are related to the processing of IP packets. 45. What source IP address does a router use by default when the traceroute command is issued?the highest configured IP address on the router Explanation: When sending an echo request message, a router will use the IP address of the exit interface as the source IP address. This default behavior can be changed by using an extended ping and specifying a specific source IP address. 46. Match each description with an appropriate IP address. (Not all options are used.)Explanation: Link-Local addresses are assigned automatically by the OS environment and are located in the block 169.254.0.0/16. The private addresses ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. TEST-NET addresses belong to the range 192.0.2.0/24. The addresses in the block 240.0.0.0 to 255.255.255.254 are reserved as experimental addresses. Loopback addresses belong to the block 127.0.0.0/8. 47. A user issues a ping 192.135.250.103 command and receives a response that includes a code of 1. What does this code represent?host
unreachable* 48. Which subnet would include the address 192.168.1.96 as a usable host address?192.168.1.64/26* Explanation: For the subnet of 192.168.1.64/26, there are 6 bits for host addresses, yielding 64 possible addresses. However, the first and last subnets are the network and broadcast addresses for this subnet. Therefore, the range of host addresses for this subnet is 192.168.1.65 to 192.168.1.126. The other subnets do not contain the address 192.168.1.96 as a valid host address. 49. Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.What are the three IPv6 addresses displayed when the route from PC1 to PC2 is traced? (Choose three.)2001:DB8:1:1::1* Explanation: Using the ipv6config command on PC2 displays the IPv6 address of PC2, which is 2001:DB8:1:4::A. The IPV6 link-local address, FE80::260:70FF:FE34:6930, is not used in route tracing. Using the tracert 2001:DB8:1:4::A command on PC1 displays four addresses: 2001:DB8:1:1::1, 2001:DB8:1:2::1 , 2001:DB8:1:3::2, and 2001:DB8:1:4::A. 50. A host is transmitting a broadcast. Which host or hosts will receive it?all hosts in the same subnet* 51. A host is transmitting a unicast. Which host or hosts will receive it?one specific host* 52. A user issues a ping 2001:db8:FACE:39::10 command and receives a response that includes a code of 3. What does this code represent?address unreachable* 53. A host is transmitting a multicast. Which host or hosts will receive it?a specially defined group of hosts* 54. A host is transmitting a multicast. Which host or hosts will receive it?a specially defined group of hosts* 55. A host is transmitting a multicast. Which host or hosts will receive it?a specially defined group of hosts* 56. A host is transmitting a multicast. Which host or hosts will receive it?a specially defined group of hosts* 57. A host is transmitting a multicast. Which host or hosts will receive it?a specially defined group of hosts* 58. A host is transmitting a broadcast. Which host or hosts will receive it?all hosts in the same subnet* 59. A host is transmitting a broadcast. Which host or hosts will receive it?all hosts in the same subnet* 60. Which is the compressed format of the IPv6 address 2001:0db8:0000:0000:0000:a0b0:0008:0001?2001:db8::a0b0:8:1* 61. Which is the compressed format of the IPv6 address fe80:09ea:0000:2200:0000:0000:0fe0:0290?fe80:9ea:0:2200::fe0:290* 62. Which is the compressed format of the IPv6 address 2002:0042:0010:c400:0000:0000:0000:0909?2002:42:10:c400::909* 63. Which is the compressed format of the IPv6 address 2001:0db8:0000:0000:0ab8:0001:0000:1000?2001:db8::ab8:1:0:1000* 64. Which is the compressed format of the IPv6 address 2002:0420:00c4:1008:0025:0190:0000:0990?2002:420:c4:1008:25:190::990* 65. Which is the compressed format of the IPv6 address 2001:0db8:0000:0000:0000:a0b0:0008:0001?2001:db8::a0b0:8:1* 66. Which is the compressed format of the IPv6 address fe80:0000:0000:0000:0220:0b3f:f0e0:0029?fe80::220:b3f:f0e0:29* 67. Which is the compressed format of the IPv6 address 2001:0db8:0000:0000:0000:a0b0:0008:0001?2001:db8::a0b0:8:1* 68. Which is the compressed format of the IPv6 address 2002:0042:0010:c400:0000:0000:0000:0909?2002:42:10:c400::909* 69. Which is the compressed format of the IPv6 address fe80:09ea:0000:2200:0000:0000:0fe0:0290?fe80:9ea:0:2200::fe0:290* 70. A user issues a ping 2001:db8:FACE:39::10 command and receives a response that includes a code of 2 . What does this code represent?beyond scope of the source address* 71. A user issues a ping 192.135.250.103 command and receives a response that includes a code of 1. What does this code represent?host unreachable* 72. A user issues a ping fe80:65ab:dcc1::100 command and receives a response that includes a code of 3. What does this code represent?address unreachable* 73. A user issues a ping 10.10.14.67 command and receives a response that includes a code of 0. What does this code represent?network unreachable* 74. A user issues a ping fe80:65ab:dcc1::100 command and receives a response that includes a code of 4. What does this code represent?port
unreachable* 75. A user issues a ping 198.133.219.8 command and receives a response that includes a code of 0. What does this code represent?network unreachable* 76. A user issues a ping 2001:db8:3040:114::88 command and receives a response that includes a code of 4. What does this code represent?port unreachable* 77. A user issues a ping 2001:db8:FACE:39::10 command and receives a response that includes a code of 2. What does this code represent?beyond scope of the source address* Modules 11 – 13: IP Addressing Exam Answers (Additional)1. What is the prefix length notation for the subnet mask 255.255.255.224?/25 2. How many valid host addresses are available on an IPv4 subnet that is configured with a /26 mask?254 3. Which subnet mask would be used if 5 host bits are available?255.255.255.0 4. A network administrator subnets the 192.168.10.0/24 network into subnets with /26 masks. How many equal-sized subnets are created?1 5. What subnet mask is represented by the slash notation /20?255.255.255.248 6. Which statement is true about variable-length subnet masking?Each subnet is the same size. 7. Why does a Layer 3 device perform the ANDing process on a destination IP address and subnet mask?to identify the broadcast address of the destination network 8. How many usable IP addresses are available on the 192.168.1.0/27 network?256 9. Which subnet mask would be used if exactly 4 host bits are available?255.255.255.224 10. Which two parts are components of an IPv4 address? (Choose two.)subnet portion 11. If a network device has a mask of /26, how many IP addresses are available for hosts on this network?64 12. What does the IP address 172.17.4.250/24 represent?network address 13. If a network device has a mask of /28, how many IP addresses are available for hosts on this network?256 14. What is the purpose of the subnet mask in conjunction with an IP address?to uniquely identify a host on a network 15. 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 16. What is indicated by a successful ping to the ::1 IPv6 address?The host is cabled properly. 17. What is the most compressed representation of the IPv6 address 2001:0000:0000:abcd:0000:0000:0000:0001?2001:0:abcd::1 18. What is the purpose of the command ping ::1?It tests the internal configuration of an IPv6 host.* 19. At a minimum, which address is required on IPv6-enabled interfaces?link-local* 20. What is the interface ID of the IPv6 address 2001:DB8::1000:A9CD:47FF:FE57:FE94/64?FE94 21. What are three parts of an IPv6 global unicast address? (Choose three.)an interface ID that is used to identify the local network for a particular host 22. What is the valid most compressed format possible of the IPv6 address 2001:0DB8:0000:AB00:0000:0000:0000:1234?2001:DB8:0:AB00::1234* 23. What is the prefix associated with the IPv6 address 2001:CA48:D15:EA:CC44::1/64?2001::/64 24. What type of address is automatically assigned to an interface when IPv6 is enabled on that interface?global unicast 25. Which IPv6 network prefix is only intended for local links and can not be routed?2001::/3 26. Your organization is issued the IPv6 prefix of 2001:0000:130F::/48 by your service provider. With this prefix, how many bits are available for your organization to create subnetworks if interface ID bits are not borrowed?8 27. What is the subnet address for the IPv6 address 2001:D12:AA04:B5::1/64?2001::/64 28. Which type of IPv6 address is not routable and used only for communication on a single subnet?global unicast address 29. Which address type is not supported in IPv6?private 30. What is the minimum configuration for a router interface that is participating in IPv6 routing?to have only a link-local IPv6 address* 31. A user calls to report that a PC cannot access the internet. The network technician asks the user to issue the command ping 127.0.0.1 in a command prompt window. The user reports that the result is four positive replies. What conclusion can be drawn based on this connectivity test?The PC can access the network. The problem exists beyond the local network. 32. Which command can be used to test connectivity between two devices using echo request and echo reply messages?netstat 33. What field content is used by ICMPv6 to determine that a packet has expired?TTL field 34. Which protocol provides feedback from the destination host to the source host about errors in packet delivery?ARP 35. Which utility uses the Internet Control Messaging Protocol (ICMP)?RIP 36. A network administrator can successfully ping the server at www.cisco.com, but cannot ping the company web server located at an ISP in another city. Which tool or command would help identify the specific router where the packet was lost or delayed?ipconfig 37. Which protocol is used by IPv4 and IPv6 to provide error messaging?ICMP* 38. What message is sent by a host to check the uniqueness of an IPv6 address before using that address?neighbor solicitation* 39. A technician is troubleshooting a network where it is suspected that a defective node in the network path is causing packets to be dropped. The technician only has the IP address of the end point device and does not have any details of the intermediate devices. What command can the technician use to identify the faulty node?Tracert* 40. A user who is unable to connect to the file server contacts the help desk. The helpdesk technician asks the user to ping the IP address of the default gateway that is configured on the workstation. What is the purpose for this ping command?to obtain a dynamic IP address from the server 41. What is a function of the tracert command that differs from the ping command when they are used on a workstation?The tracert command reaches the destination faster. 42. Which ICMP message is used by the traceroute utility during the process of finding the path between two end hosts?redirect 43. Which two things can be determined by using the ping command? (Choose two.)the number of routers between the source and destination device 44. Which statement describes a characteristic of the traceroute utility?It sends four Echo Request messages. How many networks are available on an IPv4 subnet that is configured with a 29 mask?Subnet Cheat Sheet – 24 Subnet Mask, 30, 26, 27, 29, and other IP Address CIDR Network References. How many valid host addresses are available on an IPv4 subnet that is configured with a 28 mask *?Class A. Which subnet mask would be used if 7 host bits are available?The mask of 255.255. 255.128 results in 7 host bits.
How do you calculate the number of hosts in a subnet?In simple words, the Number of hosts in any network can be calculated with the formula = 2x– 2, where x is the number of host ID bits in the IP address.
|