CompTIA Network+ Easy Subnetting / Variable Length Subnet Masks (VLSMs), Summarization, and Troubleshooting TCP/IP

Given 172.16.0.0/18, what are the valid hosts?

.0.1 - .63.254; .64.1 - .127.254; .128.1 - .191.254; & .192.1 - .255.254

Given 192.168.10.0/25, what are the valid hosts?

.1 - .126 & .129 - .254

Given 192.168.10.0/25, how many hosts are there per subnet?

126

What is the subnetwork address for a host with the IP address 200.10.5.68/28?

200.10.5.64

What is the breakout of 192.168.100.37/28?

/28 is 255.255.255.240

What is the breakout of 192.168.100.17/29?

/29 is 255.255.255.248

What is the breakout of 192.168.100.25/30?

/30 is 255.255.255.252

Given 192.168.10.0/25, what are the valid subnets?

0 & 128

Given 172.16.0.0/18, what are the valid subnets?

0.0, 64.0, 128.0, and 192.0

What is the valid broadcast of 192.168.100.25/30?

192.168.100.27

What is the valid subnet of 192.168.100.37/28?

192.168.100.32

What is the valid broadcast of 192.168.100.37/28?

192.168.100.47

What is the valid subnet of 192.168.100.66/27?

192.168.100.64

What is the valid subnet of 192.168.100.99/26?

192.168.100.64

What is the valid broadcast of 192.168.100.66/27?

192.168.100.95

You need to configure a server that is on the subnet 192.168.19.24/29. The router has the first available host address. Which of the following should you assign to the server?

192.168.19.26

You have an interface on a router with the IP address of 192.168.192.10/29. What is the broadcast address the hosts will use on this LAN?

192.168.192.15

Given 192.168.10.0/25, how many subnets are there?

2

You have an interface on a router with the IP address of 192.168.192.10/29. Including the router interface, how many hosts can have IP addresses on the LAN attached to router interface?

6

Given 172.16.0.0/18, what is the broadcast address for each subnet?

63.255, 127.255, 191.255, 255.255

The network address of 172.16.0.0/19 provides how many subnets and hosts?

8 subnets, each with 8,190 hosts.

What are the values of /29?

Binary: 11111000 Hexadecimal: F8 Dotted Decimal: 255.255.255.248

What are the values of /30?

Binary: 11111100 Hexadecimal: FC Dotted Decimal: 255.255.255.252

What do Variable Length Subnet Masks (VLSMs) do?

Create many networks using subnet masks of different lengths from one network.

What is the breakout of 192.168.100.99/25?

/25 is 255.255.255.128

What are the Class C Subnet Masks?

/25, /26, /27, /28, /29, /30

What is the breakout of 192.168.100.99/26?

/26 is 255.255.255.192

What is the breakout of 192.168.100.66/27?

/27 is 255.255.255.224

You have a Class B network and need 29 subnets. What is your mask?

/21

What is the breakout of 10.16.3.65/23?

/23 is 255.255.254.0

What is the valid subnet of 10.16.3.65/23?

10.16.3.64

What is the valid broadcast of 10.16.3.65/23?

10.16.3.65

Given 192.168.10.0/25, what is the broadcast address for each subnet?

127 & 255

Given 172.16.0.0/18, how many hosts are there per subnet?

16,382

What is the valid broadcast of 192.168.100.17/29?

192.168.100.23

What is the valid subnet of 192.168.100.25/30?

192.168.100.24

What is the valid subnet of 192.168.100.99/25?

192.168.100.0

What is the valid broadcast of 192.168.100.99/25?

192.168.100.127

What is the valid broadcast of 192.168.100.99/26?

192.168.100.127

What is the valid subnet of 192.168.100.17/29?

192.168.100.16

Given 192.168.10.0/25, what is the subnet mask?

255.255.255.128

If an Ethernet port on a router was assigned an IP address of 172.16.112.1/25, what would be the valid subnet address of this host?

255.255.255.128 255.255.255.0

What are the valid subnets?

256 - subnet mask = block size; start with 0 and add the block size until the mask value is reached.

How many subnets are there?

2^x where x is the number of masked bits (or 1's).

How many valid hosts are there per subnet?

2y - 2 where y is the number of unmasked bits.

What is a Subnet Mask?

32-bit value that allows the recipient of IP packets to distinguish the network ID portion of the IP address from the host ID portion of the IP address

Given 172.16.0.0/18, how many subnets are there?

4

What are the values of /26?

Binary: 11000000 Hexadecimal: C0 Dotted Decimal: 255.255.255.192

You have a network that needs 29 subnets while maximizing the number of host addresses available on each subnet. How many bits must you borrow from the host field to provide the correct subnet mask?

A 248 mask. This provides 32 subnets, each with 6 hosts.

What are the values of /27?

Binary: 11100000 Hexadecimal: E0 Dotted Decimal: 255.255.255.224

What are the values of /28?

Binary: 11110000 Hexadecimal: F0 Dotted Decimal: 255.255.255.240

On a VLSM network, which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses?

A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.

What are Variable Length Subnet Masks (VLSMs)?

Allows Classless Subnetting where each network segment can use a different subnet mask.

What does IP Subnet-Zero do?

Allows you to use the first and last subnet in your network design; turn this command on by default

What are the valid hosts of 192.168.100.99/25?

Between .1 and .126

What are the valid hosts of 192.168.100.17/29?

Between .17 and .22

What are the valid hosts of 192.168.100.25/30?

Between .25 and .26

What are the valid hosts of 192.168.100.37/28?

Between .33 and .46

What are the valid hosts of 192.168.100.99/26?

Between .65 and .126

What are the valid hosts of 192.168.100.66/27?

Between .65 and .96

What are the values of /25?

Binary: 10000000 Hexadecimal: 80 Dotted Decimal: 255.255.255.128

A router receives a packet on an interface with a destination address of 172.16.46.191/26. What will the router do with this packet?

Discard it; by default it will discard any broadcast packets.

How does subnet affect network topology?

Facilitates spanning of large geographical distances

Why would you be unable to Ping Loopback?

IP stack failure; Reinstall TCP/IP.

Why would you be unable to Ping Default Gateway?

Local physical network problem between NIC and router.

How does subnet affect network performance?

Optimizes it

What are the 4 Troubleshooting Steps for networking issues?

Ping 127.0.0.1 (loopback) Ping the local host Ping Default Gateway (router) Ping remote destination

Why would you be able to ping but still unable to communicate?

Possible DNS problem.

Why would you be unable to Ping Local Host?

Problem with the NIC; Replace the NIC.

What are the Classful Routing Protocols?

RIPv1 and IGRP

What are the Classless Routing Protocols?

RIPv2, EIGRP, or OSPF

How does subnet affect network traffic?

Reduces it

Why would you be unable to Ping Remote Destination?

Remote physical network problem between NIC and destination; Additional troubleshooting required at destination.

How does subnet affect network management?

Simplifies it

What subnet and broadcast address is the IP address 172.16.45.14 255.255.255.252 (/30) a member of?

Subnet .12; Broadcast .15

What subnet and broadcast address is the IP address 172.16.46.255 255.255.240.0 (/20) a member of?

Subnet .32.0; Broadcast .47.255

What subnet and broadcast address is the IP address 172.16.50.10 255.255.224.0 (/19) a member of?

Subnet .32.0; Broadcast .63.255

What subnet and broadcast address is the IP address 172.16.10.33 255.255.255.224 (/27) a member of?

Subnet .32; Broadcast .63

What is the subnet and broadcast address of the host 172.16.88.255/20?

Subnet .80.0; Broadcast .95.255

What subnet and broadcast address is the IP address 172.16.66.10 255.255.192.0 (/18) a member of?

Subnet 172.16.64.0: Broadcast 172.16.127.255

If a host on a network has the address 172.16.45.14/30, what is the subnetwork this host belongs to?

The 12 subnet.

What is the subnetwork number of a host with an IP address of 172.16.66.0/21?

The 64.0 subnet.

What's the broadcast address of each subnet?

The highest number; the broadcast of the last subnet is always 255.

You need to subnet a network that has five subnets, each with at least 16 hosts. Which classful subnet mask would you use?

The mask 255.255.255.224 provides 8 subnets, each with 30 hosts. This is /27.

What are the valid hosts in each subnet?

The subnet range -2 (One for subnet ID and one for broadcast).

What are the valid hosts of 10.16.3.65/23?

There are none.

What is the maximum number of IP addresses that can be assigned to hosts on a local subnet that uses the 255.255.255.224 subnet mask?

This provides 8 subnets, each with 30 hosts.

To test the IP stack on your local host, which IP address would you ping?

To test the local stack on your host, ping the loopback interface of 127.0.0.1.

What are additional Windows Troubleshooting methods?

Traceroute Arp -a Ipconfig /all

What are additional Cisco Troubleshooting methods?

Tracert Show ip arp

Which configuration command must be in effect to allow the use of 8 subnets if the Class C subnet mask is 255.255.255.224?

ip subnet-zero