Friday 23 June 2017

Introduction to Networks (Version 6.0) - ITN Chapter 2 Exam

1. What is the function of the kernel of an operating system?
Answer
The kernel provisions hardware resources to meet software requirements

2. A network administrator needs to keep the user ID, password, and session contents private when establishing remote CLI connectivity with a switch to manage it. Which access method should be chosen?
Answer
SSH

3. Which procedure is used to access a Cisco 2960 switch when performing an initial configuration in a secure environment?
Answer
Use the console port to locally access the switch from a serial or USB interface of the PC.

4. Which command or key combination allows a user to return to the previous level in the command hierarchy?
Answer
exit

5. A router with a valid operating system contains a configuration file stored in NVRAM. The configuration file has an enable secret password but no console password. When the router boots up, which mode will display?
Answer
user EXEC mode

6. Which two functions are provided to users by the context-sensitive help feature of the Cisco IOS CLI? (Choose two.)
Answer
a. displaying a list of all available commands within the current mode
b. determining which option, keyword, or argument is available for the entered command

7. Which information does the show startup-config command display?​
Answer
the contents of the saved configuration file in the NVRAM

8. Why is it important to configure a hostname on a device?
Answer
to identify the device during remote access (SSH or telnet)

9. Which two host names follow the guidelines for naming conventions on Cisco IOS devices? (Choose two.)
Answer
a. RM-3-Switch-2A4
b. SwBranch799

10. How does the service password-encryption command enhance password security on Cisco routers and switches?
Answer
It encrypts passwords that are stored in router or switch configuration files.

11.
chapter 2

Refer to the exhibit. A network administrator is configuring the MOTD on switch SW1. What is the purpose of this command?
Answer
to display a message when a user accesses the switch

12. While trying to solve a network issue, a technician made multiple changes to the current router configuration file. The changes did not solve the problem and were not saved. What action can the technician take to discard the changes and work with the file in NVRAM?
Answer
Issue the reload command without saving the running configuration.

13. Which statement is true about the running configuration file in a Cisco IOS device?
Answer
It affects the operation of the device immediately when modified.

14. What are two characteristics of RAM on a Cisco device? (Choose two.)
Answer
a. The configuration that is actively running on the device is stored in RAM.
b. The contents of RAM are lost during a power cycle.

15. Which interface allows remote management of a Layer 2 switch?
Answer
the switch virtual interface

16. Which interface is the default SVI on a Cisco switch?
Answer
VLAN 1

17. Why would a Layer 2 switch need an IP address?
Answer
to enable the switch to be managed remotely

18. What command can be used on a Windows PC to see the IP configuration of that computer?
Answer
ipconfig

19. A technician is adding a new PC to a LAN. After unpacking the components and making all the connections, the technician starts the PC. After the OS loads, the technician opens a browser, and verifies that the PC can reach the Internet. Why was the PC able to connect to the network with no additional configuration?
Answer
The PC was preconfigured to use DHCP.

20. What is a user trying to determine when issuing a ping 10.1.1.1 command on a PC?
Answer
if there is connectivity with the destination device

21.
chapter 2

Refer to the exhibit. A network technician is testing connectivity in a new network. Based on the test results shown in the exhibit, which device does the technician have connectivity with and which device does the technician not have connectivity with? (Choose two.)
Answer
a. connectivity: switch 2
b. no connectivity: PC-C

22.
chapter 2

Refer to the exhibit. What three facts can be determined from the viewable output of the show ip interface brief command? (Choose three.)
Answer
a. The switch can be remotely managed.
b. One device is attached to a physical interface.
c. The default SVI has been configured.
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Thursday 22 June 2017

Introduction to Networks (Version 6.0) - ITN Chapter 1 Exam

1. A company is contemplating whether to use a client/ server or a peer-to-peer network. What are the three characteristics of  a peer-to-peer network? (Choose three.)
Answer
a. easy to create
b. lacks centralized administration
c. less cost to implement

2. Which device performs the function of determining the path that message should take through internetworks?
Answer
a. a router

3. What two criteria are used to help select a network medium from various network media? (Choose two.)
Answer
a. the distance the selected medium can successfully carry a signal
b. the environment where the selected medium is to be installed

4. Which two statements describe intermediary devices? (Choose two.)
Answer
a. Intermediary devices direct the path of the data.
b. Intermediary devices connect individual hosts to the network.

5. What are two functions of end devices on a network? (Choose two.)
Answer
a. They originate the data that flows through the network.
b. They are the interface between humans and the communication network.

6. Which area of the network would a college IT staff most likely have to redesign as a direct result of many students bringing their own tablets and smartphones to school to access school resources?
Answer
a. wireless LAN

7. What type of network must a home user access in order to do online shopping?
Answer
a. the internet

8. An employee at a branch office is creating a quote for a customer. In order to do this, the employee needs to access confidential pricing information from internal servers at the Head Office. What type of network would the employee access?
Answer
a. an internet

9. Which two connection options provide an always-on, high-bandwidth Internet connection to computers in a home office? (Choose two.)
Answer
a. DSL
b. cable

10. Which two Internet connection options do not require that physical cables be run to the building? (Choose two.)
Answer
a. cellular
b. satellite

11. Which term describes the state of a network when the demand on the network resources exceeds the available capacity?
Answer
a. congestion

12. What type of network traffic requires QoS?
Answer
a. video conferencing

13. Which expression accurately defines the term bandwidth?
Answer
a. a measure of the data carrying capacity of the media

14. A network administrator is implementing a policy that requires strong, complex passwords. Which data protection goal does this policy support?
Answer
a. data confidentiality

15. Which statement describes a characteristic of cloud computing?
Answer
a. Applications can be accessed over the Internet by individual users or businesses using any device, anywhere in the world.

16. What is the Internet?
Answer
a. It provides connections through interconnected global networks.

17. Which statement describes the use of powerline networking technology?
Answer
a. A device connects to an existing home LAN using an adapter and an existing electrical outlet.

18. What security violation would cause the most amount of damage to the life of a home user?
Answer
a. capturing of personal data that leads to identity theft

19. A user is implementing security on a small office network. Which two actions would provide the minimum security requirements for this network? (Choose two.)
Answer
a. implementing a firewall
b. installing antivirus software

20. A _________________________ network is capable of delivering voice, video, text, and graphics over the same communication channels.
Answer
a. converged

21. The acronym _________________________ refers to the policy that allows employees to use their personal devices in the business office to access the network and other resources.
Answer
a. BYOD

22. Drag and Drop Questions Answers
Place the options in the following order:
podcast: an audio-based medium that allows people to deliver their recordings to a wide audience
social media: interactive websites where people create and share user-generated content with friends and family
wiki: web pages that groups of people can edit and view together
instant messaging: real-time communication between two or more people
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Saturday 10 June 2017

VPN (Virtual Private Network) - What is VPN?

VPN (Virtual Private Network)

VPN (Virtual Private Network) is a network that is constructed with the help of public medias generally by using internet to connect with the private network such as internal network of the company or organization.
VPN is the network which use public mediums like internet to connect remote office or single user with the help of secure method with the network of organization. VPN provide and ensure the security of data and information of user with the help of security procedures and tunneling protocols like layer 2 tunneling protocol (L2TP). In this process data or information is encrypted at the end of sender and decrypted at destination end.
VPN

A VPN connections which is across the internet is same as the WAN links between different websites. For the user convenience, the network resources which are extended are accessed in the same way as the resources are accessed in private network. But there is a major limitation in traditional VPNs that these VPNs are point-to-point, and they don't support or connect broadcast domains.

VPN which is well designed can provide these benefits to the company

  1. Connectivity on extended geographic
  2. Operational cost reduces as compare to traditional WANs
  3. Transit time and travelling cost reduces for remote users
  4. Improvement in productivity
  5. Network topology simplifies
  6. Opportunities for global networking improve
  7. Telecommuter support will be available
  8. Faster Return On Investment (ROI) as compare to traditional WAN

Features which are needed in well designed VPN?

  1. Security
  2. Reliability
  3. Scalability
  4. Network Management
  5. Policy Management
  6. Security Mechanisms

Security Model of VPN provides

  1. Data Confidentiality for example if the data is sniffed at the level of packet still then attacker will only see encrypted data.
  2. Authentication of sender to prevent the access of unauthorized user access to VPN.
  3. Integrity of message to detect any symptoms of data tampering during transmission.

Following things are included in Secure VPN Protocol

  1. IPsec (Internet Protocol Security)
  2. SSL/ TLS (Transport Layer Security)
  3. DTLS (Datagram Transport Layer Security)
  4. MPPE (Microsoft Point-to-Point Encryption)
  5. SSTP (Microsoft Secure Socket Tunneling Protocol)
  6. MPVPN (Multi Path Virtual Private Network)
  7. Secure Shell Host VPN
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Wednesday 31 May 2017

Firewall - Configuration of Firewall

Firewall Configurations

Firewall are also configured manually by the users which means that user can add or remove filters on the basis of different conditions and terms. Here are the some examples

IP Address

Each device on the internet is assigned by unique address and that address is known as IP Address. IP Address is based on 32 bits and is consists of four octets separated by dotted decimal numbers. IP Address typically looks line 192.168.1.254. For example, if specific ip address which does not exists in the company network is reading huge number of files from the server then firewall will block all the incoming and outgoing traffic from that ip address.

Domain Names

As we all known that it is difficult to remember the numbers which are used to make the ip address and for some times there is the need to change the ip address of the device that's why there is also the name of server like human name. For example it is easy for the user to remember www.google.com as compare to 216.58.205.36. Any company can block access to specific or all users to the some domain names or they will allow access to some specific domain names. The user who wants to connect and communicate with the server have to use the protocol which is pre-defined for that specific service. Protocols are usually in text form and they describe that how client and server will communicate with each other. Here are the some common protocols that can be used and filtered with the help of firewall are:

Internet Protocol (IP)

It is main system of delivery for information over the internet.

Transmission Control Protocol (TCP)

Used to transfer or rebuild the information which is travelling over the internet.

Hyper Text Transfer Protocol (HTTP)

This protocol is used for web pages.

File Transfer Protocol (FTP)

This protocol is used to upload and download the files from the server.

User Datagram Protocol (UDP)

This protocol is used for the transmissions which don't requires response from the user or other devices e.g., recorded or live streaming of audio and video.

Internet Control Message Protocol (ICMP)

This protocol is used by routers to exchange their information with other connected routers.

Simple Mail Transport Protocol (SMTP)

This protocol is used to transfer information which is based on text such as e-mail.

Telnet

This protocol is used to configure device remotely.

Ports

All the machines which act as server uses numbered ports of internet usage to provide their services and one port for each service on the server which available.
For example if a single server is running both the services of HTTP and FTP then HTTP uses port number 80 and FTP uses port number 21.

Specific word and phrases

Specific word and phrases will be any thing. In this process firewall examines or search the each packet which is passing through it for the information which will exactly matches with the phrase listed in it filter.
For example, you have instructed the firewall to block the packet having the word "X-Ray" then filter will only block the packet containing exactly matched word, it will not block the packet having "X Ray" (without hyphen). User can add as many as words and statements to the filter list of firewall.
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Tuesday 30 May 2017

Firewall - Definition and Detail of Firewall

Firewall

Firewall is network security system which is used to control and monitor the incoming and outgoing traffic of network with the help of rules defined in it. Firewall is basically used to built a hurdle between secure and trusted network which is also known as internal network with other network or know trusted/ secure network. Firewall are both in hardware and software forms. The main difference between them is the difference in feature and functionality of firewall. Some hardware firewalls offer other functionality such as act like DHCP server for the network to which they are protecting.
Personal computer operating system has software based firewall which protect them form threats coming from other network such as internet. Many routers which exchange data between different networks contains firewall component and same as firewalls perform basic functions of routing.
Firewall

Hardware and Software Firewall

There are both type of firewalls which are hardware and software but the configuration of ideal firewall consists of both hardware and software. Limiting access to personal computer and network, firewall is very useful for remote access to private network using certificates of secure authentication and logins.

Hardware Firewalls

Standalone hardware firewall product can be purchased but they are also found in broadband routers and considered as an important part of personal computer and network setup. Hardware firewall have four minimum number of network ports to connect personal computers with it, but for enterprise networks, networking firewall enterprise solutions are available.

Software Firewalls

Software firewalls are installed on personal computers like any other software and can be customized by allowing limited control to some functions and protection features. Software firewall basically provide protection against attempts to control or to gain access to personal computer form outside.

History of Firewalls

The term firewall basically refer to a wall having fire on it. Firewall technology comes in late 1980's when internet is new technology in its global use and connectivity terms. The predecessors for network security with firewall were routers which are used in late 1980's.

Types of Firewall

There are five type of Firewalls
  1. Packet Firewalls
  2. Stateful Firewalls
  3. Application Layer Firewalls
  4. Proxy Firewalls
  5. Network Address Translation Firewalls

Packet Firewalls

In early stages firewalls work as packet filters, by examining the each packet that is transferred form computer to the internet. When packet is traveled from packet filter firewall, it checks its source and destination addresses, its protocol type and the port number of destination against the set of rules defined in it.

Stateful Firewalls

To check the connection state of packet there is a need of firewall to record the state of all the packets which passed through it. Firewall ensures, that packet has enough information to estimate that whether a packet is start of new connection, existing connection part or not a part of any connection. This process is known as "STATEFUL PACKET EXAMINATION" and it was introduced in 1994 with the name of check point software in FireWall-1 Software Firewall and after that late in 1990's it was common feature of firewall products.

Application Layer Firewalls

As the increasing number of attacks on web servers there is the need of firewall which protect both servers and applications which are running on servers. Application layer firewall technology first comes in 1999, which examines and filter the packets on any layer of OSI model up to application layer.
The major benefit behind the filtering of application layer is to block specific contents such as introduced malware or some suspicious websites, and recognize the misuse of some protocols and applications such as HTTP, FTP an DNS.

Proxy Firewalls

Proxy Server Firewalls are operated at application layer of firewalls which act as intermediate for the requests coming from one network to another network for some specific application. These firewalls prevent the direct connection from both sides of firewall and both sides are forced to establish the connection via proxy which can allow or block the traffic using the set of rules defined in it.

Network Address Translation Firewalls

Some firewalls have the functionality of NAT (Network Address Translation) and the hosts which are protected behind the firewall are commonly assigned ip address for private ip address range. Some firewalls have the functionality of hiding the original ip address of the hosts protected by them. Basically functionality of NAT was developed to address limited rout-able addresses of IPV4 which are assigned or used by different companies or personal computers and as well as to reduce the amount of purchasing enough amount of public addresses for each computer working in organization. Hiding the addresses of devices which are protected by firewalls has become increasingly important defense against reconnaissance attack on networks.
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Thursday 25 May 2017

STP - Spanning Tree Protocol Detail and Configuration

STP (Spanning Tree Protocol)

STP (Spanning Tree Protocol) is used to prevent any network for looping of frames by keeping some ports or interfaces of device in forward state and some ports or interfaces in blocked mode.
When two or more than two switches are connected with each other to create redundant links then it may cause loop occurrence. STP is layer 2 protocol and it enabled on switches by default. STP is used to stop loop occurrence.

STP - Spanning Tree Protocol
  • STP - IEEE 802.1D (Open Standard)
  • RSTP - IEEE 802.1W
  • MST (Multiple Spanning Tree) - IEEE 802.1S
  • PVST (Per VLAN Spanning Tree) - CISCO Proprietary
  • PVST+ - CISCO Proprietary
  • RPVST - CISCO Proprietary
  • CST (Common Spanning Tree) - All VLANs will participate in single number of instance
  • IST (Inter Spanning Tree) - Different - Different VLANs Different - Different number of instance
Problems which occur if STP is not used
  • Storm of Broadcast
  • High Process Utilization
  • Instability of MAC Table
  • Transmission of Multiple Frames
Tasks performed by STP
  • Root Bridge Elect
  • Designated Port Elect
  • Root Port Elect

Root Bridge Elect

A switch having lowest best bridge ID which is the combination of switch priority and MAC addresses. This ID is consist of 8 bytes. 2 bytes for priority and 6 bytes for MAC address.
By default priority of switches is 32768.
Priority can be changed and set between 0 - 65535.

STP - Root Bridge

Designated Port Elect

Ports which advertise BPDUs having lowest cost are know as designated ports. BPDUs are sent by designated ports towards Non Root Bridge.

Root Port Elect

Port that receives the BPDUs of lowest cost is know as root port. It is the shortest path to the root bridge.
COST - Cost is an integer value which is used to perform Designated Port (DP) and Root Port (RP) elections.

Ethernet StandardsCost
10 Mbps100
100 Mbps19
1 Gbps4
10 Gbps2

BPDU (Bridge Protocol Data Unit)

Each switch send hello packet to other switch in every 2 sec and that hello packet is known as hello BPDU.
There are two types of BPDU
  1. Configuration BPDU - Sent from Root to Non-Root
  2. TCN (Topology Change Notification) BPDU - Sent from Non-Root to Root

Contents of Configuration BPDU

  1. Protocol ID is always 0
  2. Version is always 0
  3. Type of Message
  4. Flag
  5. ID of Root Bridge
  6. Cost of Root
  7. ID of Sender Bridge
  8. Priority of Sender Port
  9. Maximum Age
  10. Age of Message
  11. Hello
  12. Forward Delay

Content of TCN BPDU

  1. ID of Protocol
  2. Version
  3. Type of Message
  • Root Bridge sends configuration BPDU after every 2 seconds.
  • Cost of BPDU send by root bridge is always 0.

Root Bridge Requirements

  1. Low Bridge Priority
  2. Low MAC Address
(NOTE: COST OF BPDU GENERATED BY ROOT BRIDGE IS ALWAYS 0)

DP and RP Requirements

  1. Lower Bridge ID which is only for DP and between Root and Non Root
  2. Low Cost for DP and RP
  3. Lower Sender ID between Root to Non Root
  4. Lower Sender Port Priority between Non Root to Non Root
  5. Lower Sender Port ID

    Configurations of STP

    As we have learnt above that STP is enabled by default on all the switches, so here we will see that how the cost and priority of any interface can be changed or how to make any switch as root bridge.

    If we want to make switch as root bridge for one vlan
    Switch(config)# spanning-tree vlan 1 priority 0

    If we want to make switch as root bridge for all vlans
    Switch(config)# spanning-tree vlan 1 - 4094 priority 0

    To remove switch from root bridge
    Switch(config)# no spanning -tree vlan 1 - 4094 priority 0

    If one switch goes down then other switch becomes root bridge
    Switch(config)# spanning-tree vlan 1 - 5 root primary
    Switch(config)# spanning-tree vlan 6 - 10 root secondary

    On other switch issue the reverse commands
    Switch(config)# spanning-tree vlan 1 - 5 root secondary
    Switch(config)# spanning-tree vlan 6 - 10 root primary

    To change the cost of any interface
    Switch(config)# interface fa 0/1
    Switch(config-if)# spanning-tree vlan 1 cost 20
    Switch(config-if)# exit

    To change the priority of any port
    Switch(config)# interface fa 0/1
    Switch(config-if)# spanning-tree vlan 1 port priority 100
    Switch(config-if)# exit

    To configure port fast
    Switch(config)# interface fa 0/1
    Switch(config-if)# spanning-tree portfast

    We can also configure range to configure port fast
    Switch(config)# interface range fa 0/1 - 24
    Switch(config-if-range)# spanning-tree portfast
    Switch(config-if-range)# exit

    To stop or disable spanning tree protocol
    Switch(config)# no spanning-tree vlan 1

    Set timer for Hello Packet
    Switch(config)# spanning-tree vlan 1 hello time <select form 1 to 10 sec>

    Change Maximum age
    Switch(config)# spanning-tree vlan 1 max-age <select from 6 to 40 sec>

    Change forward delay time
    Switch(config)# spanning-tree vlan 1 forward-time <select form 4 to 30 sec>
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