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NETWORK BASICS

Network A system of interconnected computers and computerized peripherals such as printers is called computer network. This interconnection among computers facilitates information sharing among them. Computers may connect to each other by either wired or wireless media. A computer network consists of a collection of computers, printers and other equipment that is connected together so that they can communicate with each other.  


Network application
A Network application is any application running on one host and provides a communication to another application running on a different host, the application may use an existing application layer protocols such as: HTTP(e.g. the Browser and web server), SMTP(e.g. the email-client). And may be the application does not use any existing protocols and depends on the socket programming to communicate to another application. So the web application is a type of the network applications. 
There are lots of advantages from build up a network, but the th…

Answers to Written Labs


 Internet-working
Image result for review questions"
Written Lab 1.1: OSI Questions
1. The Application layer is responsible for finding the network resources broadcast from a server and adding flow control and error control (if the application developer chooses).
2. The Physical layer takes frames from the Data Link layer and encodes the 1s and 0s into a digital signal for transmission on the network medium.
3. The Network layer provides routing through an internetwork and logical addressing.
4. The Presentation layer makes sure that data is in a readable format for the Application layer.
5. The Session layer sets up, maintains, and terminates sessions between applications.
6. PDUs at the Data Link layer are called frames and provide physical addressing plus
other options to place packets on the network medium.
7. The Transport layer uses virtual circuits to create a reliable connection between two hosts.
8. The Network layer provides logical addressing, typically IP addressing and routing.
9. The Physical layer is responsible for the electrical and mechanical connections
between devices.
10. The Data Link layer is responsible for the framing of data packets.
11. The Session layer creates sessions between different hosts’ applications.
12. The Data Link layer frames packets received from the Network layer.
13. The Transport layer segments user data.
14. The Network layer creates packets out of segments handed down from the
Transport layer.

Chapter 1: Internet-working 

15. The Physical layer is responsible for transporting 1s and 0s (bits) in a digital signal.
16. Segments, packets, frames, bits
17. Transport
18. Data Link
19. Network
20. 48 bits (6 bytes) expressed as a hexadecimal number
Written Lab 1.2: Defining the OSI Layers and Devices
Description Device or OSI Layer
This device sends and receives information about the Network layer.
Router
This layer creates a virtual circuit before transmitting
between two end stations.
Transport
This device uses hardware addresses to filter a network. Bridge or switch
Ethernet is defined at these layers. Data Link and Physical
This layer supports flow control, sequencing, and acknowledgments.
Transport
This device can measure the distance to a remote network. Router
Logical addressing is used at this layer. Network
Hardware addresses are defined at this layer. Data Link (MAC sub-layer)
This device creates one big collision domain and one large
broadcast domain.
Hub
This device creates many smaller collision domains, but the
network is still one large broadcast domain.
Switch or bridge
This device can never run full-duplex. Hub
This device breaks up collision domains and broadcast
domains.
Router
970 Appendix A u Answers to Written Labs
Written Lab 1.3: Identifying Collision and
Broadcast Domains
A. Hub: One collision domain, one broadcast domain
B. Bridge: Two collision domains, one broadcast domain
C. Switch: Four collision domains, one broadcast domain
D. Router: Three collision domains, three broadcast domains
Chapter 2: Ethernet Networking
and Data Encapsulation
Written Lab 2.1: Binary/Decimal/Hexadecimal Conversion
Decimal 128 64 32 16 8 4 2 1 Binary
192 1 1 0 0 0 0 0 0 11000000
168 1 0 1 0 1 0 0 0 10101000
10 0 0 0 0 1 0 1 0 00001010
15 0 0 0 0 1 1 1 1 00001111

Decimal 128 64 32 16 8 4 2 1 Binary
172 1 0 1 0 1 1 0 0 10101100
16 0 0 0 1 0 0 0 0 00010000
20 0 0 0 1 0 1 0 0 00010100
55 0 0 1 1 0 1 1 1 00110111
Decimal 128 64 32 16 8 4 2 1 Binary
10 0 0 0 0 1 0 1 0 00001010
11 0 0 0 0 1 0 1 1 00001011
12 0 0 0 0 1 1 0 0 00001100
99 0 1 1 0 0 0 1 1 01100011
Binary 128 64 32 16 8 4 2 1 Decimal
11001100 1 1 0 0 1 1 0 0 204
00110011 0 0 1 1 0 0 1 1 51
10101010 1 0 1 0 1 0 1 0 170
01010101 0 1 0 1 0 1 0 1 85
972 Appendix A u Answers to Written Labs
Binary 128 64 32 16 8 4 2 1 Decimal
11000110 1 1 0 0 0 1 1 0 198
11010011 1 1 0 1 0 0 1 1 211
00111001 0 0 1 1 1 0 0 1 57
11010001 1 1 0 1 0 0 0 1 209
Binary 128 64 32 16 8 4 2 1 Decimal
10000100 1 0 0 0 0 1 0 0 132
11010010 1 1 0 1 0 0 1 0 210
10111000 1 0 1 1 1 0 0 0 184
10100110 1 0 1 0 0 1 1 0 166
3.
Binary 128 64 32 16 8 4 2 1 Hexadecimal
11011000 1 1 0 1 1 0 0 0 D8
00011011 0 0 0 1 1 0 1 1 1B
00111101 0 0 1 1 1 1 0 1 3D
01110110 0 1 1 1 0 1 1 0 76

Binary 128 6 32 16 8 4 2 1 Hexadecimal
11001010 1 1 0 0 1 0 1 0 CA
11110101 1 1 1 1 0 1 0 1 F5
10000011 1 0 0 0 0 0 1 1 83
11101011 1 1 1 0 1 0 1 1 EB
Binary 128 64 32 16 8 4 2 1 Hexadecimal
10000100 1 0 0 0 0 1 0 0 84
11010010 1 1 0 1 0 0 1 0 D2
01000011 0 1 0 0 0 0 1 1 43
10110011 1 0 1 1 0 0 1 1 B3

Written Lab 2.2: CSMA/CD Operations

When a collision occurs on an Ethernet LAN, the following happens:
1. A jam signal informs all devices that a collision occurred.
2. The collision invokes a random back-off algorithm.
3. Each device on the Ethernet segment stops transmitting for a short time until the
timers expire.
4. All hosts have equal priority to transmit after the timers have expired.

Written Lab 2.3: Cabling

1. Crossover
2. Straight-through
3. Crossover
4. Crossover
5. Straight-through
6. Crossover
7. Crossover
8. Rolled

 Answers to Written Labs

Written Lab 2.4: Encapsulation

At a transmitting device, the data encapsulation method works like this:
1. User information is converted to data for transmission on the network.
2. Data is converted to segments, and a reliable connection is set up between the transmitting and receiving hosts.
3. Segments are converted to packets or datagrams, and a logical address is placed in the
header so each packet can be routed through an internetwork.
4. Packets or datagrams are converted to frames for transmission on the local network.
Hardware (Ethernet) addresses are used to uniquely identify hosts on a local net￾work segment.
5. Frames are converted to bits, and a digital encoding and clocking scheme is used.
Chapter 3: Introduction to TCP/IP
Written Lab 3.1: TCP/IP
1. 192 through 223, 110xxxxx
2. Host-to-host
3. 1 through 126
4. Loopback or diagnostics
5. Turn all host bits off.
6. Turn all host bits on.
7. 10.0.0.0 through 10.255.255.255
8. 172.16.0.0 through 172.31.255.255
9. 192.168.0.0 through 192.168.255.255
10. 0 through 9 and A, B, C, D, E, and F
Written Lab 3.2: Mapping Applications to the DoD Model
1. Internet
2. Process/Application
3. Process/Application
4. Process/Application
5. Process/Application
6. Internet
7. Process/Application
8. Host-to-host
9. Process/Application
10. Host-to-host
11. Process/Application
12. Internet
13. Internet
14. Internet
15. Process/Application
16. Process/Application
17. Process/Application

Written Lab 4.1: Written Subnet Practice #1

1. 192.168.100.25/30. A /30 is 255.255.255.252. The valid subnet is 192.168.100.24,
broadcast is 192.168.100.27, and valid hosts are 192.168.100.25 and 26.
2. 192.168.100.37/28. A /28 is 255.255.255.240. The fourth octet is a block size of 16.
Just count by 16s until you pass 37. 0, 16, 32, 48. The host is in the 32 subnet, with a
broadcast address of 47. Valid hosts 33–46.
3. A /27 is 255.255.255.224. The fourth octet is a block size of 32. Count by 32s until
you pass the host address of 66. 0, 32, 64, 96. The host is in the 64 subnet, and the
broadcast address is 95. Valid host range is 65–94.
4. 192.168.100.17/29. A /29 is 255.255.255.248. The fourth octet is a block size of 8. 0,
8, 16, 24. The host is in the 16 subnet, broadcast of 23. Valid hosts 17–22.
5. 192.168.100.99/26. A /26 is 255.255.255.192. The fourth octet has a block size of 64.
0, 64, 128. The host is in the 64 subnet, broadcast of 127. Valid hosts 65–126.
6. 192.168.100.99/25. A /25 is 255.255.255.128. The fourth octet is a block size of 128.
0, 128. The host is in the 0 subnet, broadcast of 127. Valid hosts 1–126.
7. A default Class B is 255.255.0.0. A Class B 255.255.255.0 mask is 256 subnets, each
with 254 hosts. We need fewer subnets. If we used 255.255.240.0, this provides 16
subnets. Let’s add one more subnet bit. 255.255.248.0. This is 5 bits of subnetting,
which provides 32 subnets. This is our best answer, a /21.
8. A /29 is 255.255.255.248. This is a block size of 8 in the fourth octet. 0, 8, 16. The
host is in the 8 subnet, broadcast is 15.
9. A /29 is 255.255.255.248, which is 5 subnet bits and 3 host bits. This is only 6 hosts
per subnet.
10. A /23 is 255.255.254.0. The third octet is a block size of 2. 0, 2, 4. The subnet is in the
16.2.0 subnet; the broadcast address is 16.3.255.
Written Lab 4.2: Written Subnet Practice #2
 Written Lab 4.3: Written Subnet Practice #3
Classful Address Subnet Mask Number of Hosts per Subnet (2x – 2)
/16 255.255.0.0 65,534
/17 255.255.128.0 32,766
/18 255.255.192.0 16,382
/19 255.255.224.0 8,190
/20 255.255.240.0 4,094
/21 255.255.248.0 2,046
/22 255.255.252.0 1,022
/23 255.255.254.0 510
/24 255.255.255.0 254
/25 255.255.255.128 126
/26 255.255.255.192 62
/27 255.255.255.224 30
/28 255.255.255.240 14
/29 255.255.255.248 6
/30 255.255.255.252 2
Chapter 5: VLSMs, Summarization and Troubleshooting TCP/IP 977
Written Lab 4.3: Written Subnet Practice #3
Decimal IP Address
Address
Class
Number of Subnet
and Host Bits
Number of Subnets (2x)
Number of Hosts
(2x – 2)
10.25.66.154/23 A 15/9 32,768 510
172.31.254.12/24 B 8/8 256 254
192.168.20.123/28 C 4/4 16 14
63.24.89.21/18 A 10/14 1,024 16,382
128.1.1.254/20 B 4/12 16 4,094
208.100.54.209/30 C 6/2 64 2
Chapter 5: VLSMs, Summarization and
Troubleshooting TCP/IP
1. 192.168.0.0/20
2. 172.144.0.0 255.240.0.0
3. 192.168.32.0 255.255.224.0
4. 192.168.96.0 255.255.240.0
5. 66.66.0.0 255.255.240.0
6. 192.168.0.0/17
7. 172.16.1.0 255.255.248.0
8. 192.168.128.0 255.255.192.0
9. 53.60.96.0 255.255.224.0
10. 172.16.0.0 255.255.192.0
 Answers to Written Labs
Chapter 6: Cisco’s Internetworking
Operating System (IOS)
Written Lab 6
1. Router(config)#clock rate 1000000
2. Switch#config t
switch config)# line vty 0 15
switch(config-line)# no login
3. Switch#config t
Switch(config)# int f0/1
Switch(config-if)# no shutdown
4. Switch#erase startup-config
5. Switch#config t
Switch(config)# line console 0
Switch(config)# password todd
Switch(config)# login
6. Switch#config t
Switch(config)# enable secret cisco
7. Router#show controllers serial 0/2
8. Switch#show terminal
9. Switch#reload
10. Switch#config t
Switch(config)#hostname Sales
Chapter 7: Managing a Cisco Internetwork
Written Lab 7.1: IOS Management
1. copy start run
2. show cdp neighbor detail or show cdp entry *
3. show cdp neighbor
Chapter 8: IP Routing 979
4. Ctrl+Shift+6, then X
5. show sessions
6. Either copy tftp run or copy start run
7. NTP
8. ip helper-address
9. ntp server ip_address version 4
10. show ntp status
Written Lab 7.2: Router Memory
1. Flash memory
2. ROM
3. NVRAM
4. ROM
5. RAM
6. RAM
7. ROM
8. ROM
9. RAM
10. RAM
Chapter 8: IP Routing
1. router(config)#ip route 172.16.10.0 255.255.255.0 172.16.20.1 150
2. It will use the gateway interface MAC at L2 and the actual destination IP at L3.
3. router(config)#ip route 0.0.0.0 0.0.0.0 172.16.40.1
4. Stub network
5. Router#show ip route
6. Exit interface
7. False. The MAC address would be the router interface, not the remote host.
8. True
9. router(config)#router rip
router(config-router)#passive-interface S1
10. True
980 Appendix A u Answers to Written Labs
Chapter 9: Open Shortest Path
First (OSPF)
1. router ospf 101
2. show ip ospf
3. show ip ospf interface
4. show ip ospf neighbor
5. show ip route ospf
Chapter 10: Layer 2 Switching
1. show mac address-table
2. Flood the frame out all ports except the port on which it was received
3. Address learning, forward/filter decisions, and loop avoidance
4. It will add the source MAC address in the forward/filter table and associate it with the
port on which the frame was received.
5. Maximum 1, violation shutdown
Chapter 11: VLANs and
InterVLAN Routing
1. False! You do not provide an IP address under any physical port.
2. STP
3. Broadcast
4. Collision
5. switch-port trunk encapsulation dot1q
6. Trunking allows you to make a single port part of multiple VLANs at the same time.
7. Frame identification (frame tagging) uniquely assigns a user-defined ID to each frame.
This is sometimes referred to as a VLAN ID or color.
8. True
9. Access link
10. switch-port trunk native vlan 4
Chapter 13: Network Address Translation 981
Chapter 12: Security
1. access-list 10 deny 172.16.0.0 0.0.255.255
access-list 10 permit any
2. ip access-group 10 out
3. access-list 10 deny host 192.168.15.5
access-list 10 permit any
4. show access-lists
5. IDS, IPS
6. access-list 110 deny tcp host
172.16.10.1 host 172.16.30.5 eq 23
access-list 110 permit ip any any
7. line vty 0 4
access-class 110 in
8. ip access-list standard No172Net
deny 172.16.0.0 0.0.255.255
permit any
9. ip access-group No172Net out
10. show ip interfaces
Chapter 13: Network Address Translation
1. Port Address Translation (PAT), also called NAT Overload
2. debug ip nat
3. show ip nat translations
4. clear ip nat translations *
5. Before
6. After
7. show ip nat statistics
8. The ip nat inside and ip nat outside commands
9. Dynamic NAT
10. prefix-length
982 Appendix A u Answers to Written Labs
Chapter 14: Internet Protocol
Version 6 (IPv6)
Written Lab 14.1
1. Unicast
2. Global unicast
3. Link-local
4. Unique local (used to be called site-local)
5. Multicast
6. Anycast
7. OSPFv3
8. ::1
9. FE80::/10
10. FC00:: /7
Written Lab 14.2
1. 2001:db8:1:1:090c:abff:fecd:1234
2. 2001:db8:1:1: 040c:32ff:fef1:a4d2
3. 2001:db8:1:1:12:abff:fecd:1234
4. 2001:db8:1:1:0f01:3aff:fe2f:1234
5. 2001:db8:1:1:080c:abff:feac:caba
Chapter 15: Enhanced Switch
Technologies
1. PAgP
2. show spanning-tree summary
3. 802.1w
4. STP
5. BPDU Guard
Chapter 16: Managing Cisco Devices 983
6. (config-if)#spanning-tree portfast
7. Switch#show etherchannel port-channel
8. Switch(config)#spanning-tree vlan 3 root primary
9. show spanning-tree, then follow the root port that connects to the root bridge using
CDP, or show spanning-tree summary.
10. Active and Passive
Chapter 16: Managing Cisco Devices
Written Lab 16.1: IOS Management
1. copy flash tftp
2. 0x2101
3. 0x2102
4. 0x2100
5. UDI
6. 0x2142
7. boot system
8. POST test
9. copy tftp flash
10. show license
Written Lab 16.2: Router Memory
1. Flash memory
2. ROM
3. NVRAM
4. ROM
5. RAM
6. RAM
7. ROM
8. ROM
9. RAM
10. RAM
984 Appendix A u Answers to Written Labs
Chapter 17: IP Services
1. show standby
2. show glbp
3. GLBP
4. NetFlow
5. 5
6. SNMP
7. 4
8. show ip cache flow
9. logging ip_address
10. The AVG
Chapter 18: Troubleshooting IP, IPv6,
and VLANs
1. The INCMP is an incomplete message, which means a neighbor solicitation message
has been sent but the neighbor message has not yet been received.
2. switchport trunk native vlan 66
3. Access, auto, desirable, nonegotiate, and trunk (on)
4. Verify that the default gateway is correct. Verify that name resolution settings are
correct. Verify that there are no ACLs blocking traffic.
5. ping ::1
Chapter 19: Enhanced IGRP
1. ipv6 router eigrpv as
2. FF02::A
3. False
4. The routers will not form an adjacency
5. Passive interface
Chapter 21: Wide Area Networks 985
Chapter 20: Multi-Area OSPF
1. Type 5 or type 7
2. 2WAY
3. Type 3, and possibly Type 4 and 5
4. When all LSAs have synchronized with a neighbor on a point-to-point link
5. True
6. EXCHANGE
7. Type 1
8. ipv6 ospf 1 area 0
9. OSPFv2 and v3 use the same items when forming an adjacency: hello and dead timers,
subnet info, and area ID all must match; authentication must also match if configured.
10. and show ipv6 protocols
Chapter 21: Wide Area Networks
1. sh int s0/0
2. config t
int s0/0
encap ppp
3. config t
username todd password cisco
4. config t
int serial0/0
ppp authentication chap
5. config t
int s0/0
frame interface-dlci 16
int s0/1
frame interface-dlci 17
 Appendix A u Answers to Written Labs
6. config t
int s0/0
no ip address
encap frame
int s0/0.16 point-to-point
ip address 172.16.60.1 255.255.255.0
frame interface-dlci 16
7. PPPoE or PPPoA
8. HDLC, LCP, and NCP
9. IPsec
10. Remote access VPNs, site-to-site VPNs, and extranet VPNs

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