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Showing posts with label CCNA: Subnet masking. Show all posts
Showing posts with label CCNA: Subnet masking. Show all posts
Thursday, 5 September 2013

Mac OS X: How to manually add a Windows shared printer

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Mac OS X: How to manually add a Windows shared printer

In some situations, you may be unable to locate a Microsoft Windows shared (SMB) printer while adding a printer, yet you can still add the printer manually if you know the name or address of the Windows computer sharing the printer and the name of the shared printer.

Mac OS X v10.5 or later
  1. Choose System Preferences from the Apple menu.
  2. Choose Print & Fax from the View menu.
  3. Click the + button to add a printer.
  4. Press the Control key while clicking the "Default" icon (or any other icon on the toolbar), then choose Customize Toolbar from the contextual menu that appears.
  5. Drag the Advanced (gear) icon to the toolbar.
  6. Click Done.
  7. Click the Advanced icon that was added to the toolbar.
  8. Choose Windows from the Type pop-up menu.
  9. In the URL field, type the printer's address in one of the following formats:

    smb://workgroup/server/sharename
    smb://server/sharename

    Note: "workgroup" is the name of the Windows workgroup that the computer sharing the printer belongs to. "server" is the name of the computer sharing the printer (or its IP address). "sharename" is the shared Windows printer's share name. If the share name contains spaces, replace each space with "%20" (without quotation marks).

    Tip: You don't need a "workgroup" when specifying the IP address of the computer (such as when the printer is on a different subnet), or if your Mac belongs to the same Windows (SMB) workgroup.
  10. In the Name field, type the name you would like to use for this printer in Mac OS X.
  11. Choose the appropriate PPD or printer driver from the "Print Using" pop-up menu.
  12. Click Add.
     
Mac OS X v10.3 through v10.4.11
  1. Open Printer Setup Utility (located in /Applications/Utilities).
  2. Mac OS X 10.4.x: Choose Add Printer from the Printers menu, then hold the Option key while clicking the "More Printers" button.

    Mac OS X 10.3.x: Hold the Option key while choosing Add Printer from the Printers menu.
     
  3. Choose Advanced from the first pop-up menu.
  4. Choose "Windows Printer via SAMBA" from the Device pop-up menu.
  5. In the Device Name field, type the name you would like to use for this printer in Mac OS X.
  6. In the Device URL field, use one of the following formats to link to the printer:

    smb://user:password@workgroup/server/sharename
    smb://user:password@server/sharename
    smb://workgroup/server/sharename
    smb://server/sharename

    Notes: "user" is the name of a Windows user who has privileges to use the printer. "password" is the password of that Windows user. "workgroup" is the name of the Windows workgroup to which the computer sharing the printer belongs. "server" is the name of the computer sharing the printer or its IP address. "sharename" is the shared Windows printer's share name.

    Tip: You don't need a "workgroup" when specifying the IP address of the computer (such as when the printer is on a different subnet), or if your Mac belongs to the same Windows (SMB) workgroup.
     
  7. Choose the appropriate PPD or printer driver from the "Printer Model" pop-up menu.
  8. Click Add.
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Wednesday, 14 August 2013

Wireless Networking Tutorials

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Wireless Networking Tutorials


Select your Operating System from the list below for the step-by-step instructions:

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Monday, 12 August 2013

Laynetworks

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Laynetworks

Based in India, Laynetworks is a nob-profit organization that provides free information for students related to computer science, including specific topics on networking. The tutorials do not lead to credit, but students can access the information online for free on a Web page. The Subnetting tutorial provides background information on IP (Internet protocol) addresses and networking.
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Saturday, 10 August 2013

CCNA: Cisco IOS An Introduction

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CCNA: Cisco IOS An Introduction

Cisco IOS (short for Internetwork Operating System) is the software used on a majority of Cisco Systems routers and switches.  IOS consists of routing, switching, internetworking and telecommunications functions in a multitasking operating system.
Cisco IOS has uses command line interface (CLI), and provides a fixed set of multiple-word commands. A Cisco IOS command line interface can be accessed through either a console connection, modem connection, or a telnet session. The set of commands available at any particular level is determined by the "mode" and the privilege level of the current user.
Cisco IOS follows a command hierarchy, with each level offering different set of commands  All commands are assigned a privilege level, from 0 to 15, and can only be accessed by users with the necessary privilege. Through the CLI, the commands available to each privilege level can be defined.
Some of the widely used command hierarchy levels are given below:
User EXEC level: This is the level that a connected user is allowed initially. User EXEC allows access to a limited set of basic monitoring commands. A ">" sign denotes User EXEC mode.
Privileged EXEC level: Privileged EXEC level allows access to all router commands including router configuration and management commands. This level is usually password protected for security reasons. A "#"sign denotes privileged EXEC mode.
When a user is connected to a Cisco IOS, a User EXEC prompt appears. Now, the user can enter privileged EXEC mode by typing the password shown as below:
Router> enable
Password: [enable password]
Router# configure terminal
Router(config)#
Global configuration mode: "Global configuration mode" provides commands to change the system's configuration. This is typically represented by "(config)#" sign as shown in the above example.
Interface configuration mode: "Interface configuration mode" provides commands to change the configuration of a specific interface of the router.  An interface configuration mode is denoted by "(config-in)#".
A summary of Cisco IOS router command prompt is given below:
Prompt Explanation
Router> User EXEC mode
Router# Privileged EXEC mode
Router(config)# Global configuration mode. # sign indicates this is only accessible at privileged EXEC mode.
Router(config-if)# Interface level configuration mode.
Router(config-router)# Routing engine level within configuration mode.
Router(config-line)# Line level (vty, tty, async) within configuration mode.

Context Sensitive Help

Cisco IOS CLI offers context sensitive help. At any time during an EXEC session, a user can type a question mark (?) to get help.
Two types of context sensitive help are available:
  • Word help and
  • Command syntax help.
Word help: Word help can be used to obtain a list of commands that begin with a given character string. To use word help, type in the characters in question followed immediately by the question mark (?).  The following is an example of word help:
Router# co?
configure connect copy
Command syntax help: Command syntax help can be used to obtain a list of commands, keyword, or argument options that are available starting with the keywords that the user had already entered. To use command syntax help, enter a question mark (?) after hitting a space.  The router will then display a list of available command options with <cr> standing for carriage return. The following is an example of command syntax help:
Router# configure ?
memory Configure from NV memory
network Configure from a TFTP network host
terminal Configure from the terminal
<cr>

Cisco IOS also allows abbreviated commands support. For example, consider the following:
Router#configure terminal
Router(config)#
Router#config term
Router(config)#
Both the above commands to the same job. The IOS correctly interprets the full command words. However, if there is any ambiguity, an error message is generated as below:
Router(config)#c
% Ambiguous command: "c"
Checkout a ccna router simulator available from certexams.com.
Example Question: 
What is the command used to add a banner to a Cisco router configuration?
A. add banner
B. banner motd #
C. motd banner #
D. add banner #

Correct answer: B

Explanation:
The banner is displayed whenever anyone logs in to your Cisco router. The syntax is
"banner motd # 
MOTD stands for "Message Of The Day".
# symbol signifies the start of the banner message to the router. You will be prompted for the
message to be displayed. You need to enter "#" symbol at the end of the message, signifying
that the msg has ended.
Alternatively, you can enter the banner in the same line as below:
"banner motd # your message here#
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CCNA: Routing Fundamentals

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CCNA: Routing Fundamentals

When IP packets travel over the Internet, routing information is exchanged between the devices that control the flow of information over the Internet. These devices are known as routers, and they use the IP address as the basis for controlling the traffic. These devices need to talk the same language to function properly, though they belong to different administrative domains. For example, one router may be in Newyork(US), and the receiving router may be in London (UK). It is necessary that a routing protocol is followed for smooth flow of traffic. Given below are the widely used routing protocols for routing Internet traffic:
  • RIP v1
  • RIP v2
  • OSPF
  • IGRP
  • EIGRP
  • BGP
Notations used: Routing Information Protocol (RIP), Open Shortest Path First (OSPF), Interior Gateway Routing Protocol (IGRP), Enhanced Interior Gateway Routing Protocol (EIGRP), and Border Gateway Protocol (BGP).
One often get confused between a routing protocol and a routed protocol. A routing protocol such as RIP is used to route information packets over the Internet, where as a routed protocol such as IP (or IPX) is the payload (contains data) that get routed from source to the destination.
Routing protocols are primarily distinguished into three types:
  • Distance Vector Protocols
  • Link State Protocols
  • Hybrid Protocols
RIP is an example of distance vector protocol. IS-IS is an example of Hybrid protocol, and OSPF is an example of Link State Protocol.
The table below provides the routing protocol used with different routed protocols:
Routing Protocol Routed Protocol
RIP, OSPF,IS-IS, BGP,EIGRP IP
RIP, NLSP, EIGRP IPX
RTMP, EIGRP AppleTalk
The list of routed, and routing protocols given in the above table is not complete, and given to serve as an example only.
Routing Metric: This is a fundamental measure that routing protocols use for determining appropriate route to deliver packets. Each routing protocol uses its own measure of metric, and a sample of routing metrics used by different routing protocols is given below:
Routing Protocol Metric
RIPv2 Hop count
EIGRP Bandwidth, Delay, Load, Reliability, and MTU
OSPF Cost (Higher bandwidth indicates lower cost)
IS-IS Cost
The best route in RIP is determined by counting the number of hops required to reach the destination. A lower hop count route is always preferred over a higher hop count route. One disadvantage of using hop count as metric is that if there is a route with one additional hop, but with significantly higher bandwidth, the route with smaller bandwidth is taken. This is illustrated in the figure below:

The RIP routed packets take the path through 56KBPS link since the destination can be reached in one hop. Though, the alternative provides a minimum bandwidth of 1MBPS (though using two links of 1MBPS, and 2MBPS each), it represents 2 hops and not preferred by the RIP protocol.

Link State vs. Distance Vector

Distance Vector routing protocols usually send their entire routing table to their nearest neighbors at regular intervals. A router that receives several such routing tables filter the routes and arrive at its own and retransmits it to its neighbouring routers. There will some period of time where different routers hold non-optimized routes initially. After some time, known as convergence time, a final routing table is arrived at by all the routers. A faster convergence time results in a stable network. 
RIP, as mentioned earlier uses hop count as the metric for computing a route to a given destination. Other Distance Vector routing protocols, such as IGRP, improve on this by using hop count, bandwidth, current load, cost, and reliability to determine the best path.
Link State routing protocols usually send only the routing changes to every other router within their area. Unlike Distance Vector, routers using Link State routing protocols maintain a picture of the entire network. A router can use this network wide information to determine the best route for traffic.
Example Question:
What is true about IP routing?
A. The frame changes at each hop
B. The source IP address changes at each hop
C. The destination IP address changes at each hop
D. The hardware interface addresses remain constant

Correct answer: A

Explanation:
IP Packets are transported from source network to the destination network by what is known as routing. Hop-by-hop routing model is used by the Internet for delivery of packets. At each hop, the destination IP address is examined, the best next hop is determined by the routing protocol (such as RIP, OSPF or BGP) and the packet is forwarded by one more hop through this route. The same process takes place at the next hop. During this process, the logical addresses remain same. In an IP network, the logical addresses are IP addresses. The hardware interface addresses, such as MAC address change with each hop.
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CCNA: Subnet masking -II

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CCNA: Subnet masking -II

What we discussed in the previous section is Classful subnet masking. A Subnetmask normally contains the host portion of the bits also. This is called Classless Inter Domain Routing (CIDR). This will enable more networks for a given class of network address. For example, allowing 3 host bits towards subnet portion in our previous IP address, will allow us to offer 2X2X2 or 8 additional subnetworks. Traditionally, all zeros, and all ones subnets are not used, and hence we are left with 6 subnets.
192.189.210.078: 1100 0000.1011 1101.1101 0010.0100 1110 Class C IP Address
255.255.255.224: 1111 1111.1111 1111.1111 1111.1110 0000 Class C subnet mask with 3 additional bits of host portion used for Subnetting.
Broadcast address: 1100 0000.1011 1101.1101 0010.0101 1111 :192.189.210.95
The above is the broadcast address for a given subnet (192.189.210.078). Under Classful routing, the broadcast address would have been 192.189.210.255.
Note that by using Subnetting, we are able to increase the number of networks available within a given IP address. On the otherhand, we will be loosing the number of hosts available within a subnet to 2or 16 hosts per subnet. Again, all zeros, and all ones host addresses are traditionally reserved for other purposes.
CIDR (Classless InterDomain Routing) notation: Subnet mask is also represented as below:
192.189.210.078/27, where 27 is the number of bits in the network portion of the IP address.
Why use CIDR?
Normally, ISPs allocate the IP addresses for individuals or Corporates.  The reason being that it is almost impossible to allocate a classful IP address to every individual or a corporate. Using CIDR, the biggest ISPs are given large pool of IP address space. The ISP's customers such as individual or Corporates are then allocated networks from the big ISP's pool. This kind of arrangement will enable efficient management and utilization of the Internet.
Classful addresses can easily be written in CIDR notation
Class A =  A.B.C.D/8, Class B = A.B.C.D/16, and Class C = A.B.C.D/24
Where A,B,C,D are dotted decimal octets.
Example Question:
You have an IP of 156.233.42.56 with a subnet mask of 7 bits. How many hosts and subnets are possible?
A. 126 hosts and 510 subnets
B. 128 subnets and 512 hosts
C. 510 hosts and 126 subnets
D. 512 subnets and 128 hosts

Correct answer: C
Explanation:
Class B network has the form N.N.H.H, the default subnet mask is 16 bits long.
There is additional 7 bits to the default subnet mask. The total number of bits in subnet are 16+7 = 23.
This leaves us with 32-23 =9 bits for assigning to hosts.
7 bits of subnet mask corresponds to (2^7-2)=128-2 = 126 subnets.
9 bits belonging to host addresses correspond to (2^9-2)=512-2 = 510 hosts.
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CCNA: Subnet masking

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CCNA: Subnet masking

Subnetting an IP Network is done primarily for better utilization of available IP address space, and routing purpose. Other reasons include better organization, use of different physical media (such as Ethernet, WAN, etc.),  and securing network resources.
A subnet mask enables you to identify the network and node parts of the address. The network bits are represented by the 1s in the mask, and the node bits are represented by the 0s. A logical AND operation between the IP address and the subnet mask provides the Network Address.
For example, using our test IP address and the default Class C subnet mask, we get:
192.189.210.078: 1100 0000.1011 1101.1101 0010.0100 1110 Class C IP Address
255.255.255.000: 1111 1111.1111 1111.1111 1111.0000 0000 Default Class C subnet mask
192.189.210.0         1100 0000 1011 1101 1101 0010 0000 0000
As can be seen above, by using and AND operator, we can compute the network portion of an IP address.  The network portion for the IP address given in the above example is 192.189.210.0, and the host portion of the IP address is 078.
Given below is a table that provides binary equivalent of decimal values.  For binary conversion, take first octet of a given IP address (in dotted decimal form), and lookup the binary value. Then take the second octet and lookup the binary value, and so on.
Binary Conversion Table
Decimal Binary Decimal Binary Decimal Binary Decimal Binary
0 0000 0000 64 0100 0000 128 1000 0000 192 1100 0000
1 0000 0001 65 0100 0001 129 1000 0001 193 1100 0001
2 0000 0010 66 0100 0010 130 1000 0010 194 1100 0010
3 0000 0011 67 0100 0011 131 1000 0011 195 1100 0011
4 0000 0100 68 0100 0100 132 1000 0100 196 1100 0100
5 0000 0101 69 0100 0101 133 1000 0101 197 1100 0101
6 0000 0110 70 0100 0110 134 1000 0110 198 1100 0110
7 0000 0111 71 0100 0111 135 1000 0111 199 1100 0111
8 0000 1000 72 0100 1000 136 1000 1000 200 1100 1000
9 0000 1001 73 0100 1001 137 1000 1001 201 1100 1001
10 0000 1010 74 0100 1010 138 1000 1010 202 1100 1010
11 0000 1011 75 0100 1011 139 1000 1011 203 1100 1011
12 0000 1100 76 0100 1100 140 1000 1100 204 1100 1100
13 0000 1101 77 0100 1101 141 1000 1101 205 1100 1101
14 0000 1110 78 0100 1110 142 1000 1110 206 1100 1110
15 0000 1111 79 0100 1111 143 1000 1111 207 1100 1111
               
16 0001 0000 80 0101 0000 144 1001 0000 208 1101 0000
17 0001 0001 81 0101 0001 145 1001 0001 209 1101 0001
18 0001 0010 82 0101 0010 146 1001 0010 210 1101 0010
19 0001 0011 83 0101 0011 147 1001 0011 211 1101 0011
20 0001 0100 84 0101 0100 148 1001 0100 212 1101 0100
21 0001 0101 85 0101 0101 149 1001 0101 213 1101 0101
22 0001 0110 86 0101 0110 150 1001 0110 214 1101 0110
23 0001 0111 87 0101 0111 151 1001 0111 215 1101 0111
24 0001 1000 88 0101 1000 152 1001 1000 216 1101 1000
25 0001 1001 89 0101 1001 153 1001 1001 217 1101 1001
26 0001 1010 90 0101 1010 154 1001 1010 218 1101 1010
27 0001 1011 91 0101 1011 155 1001 1011 219 1101 1011
28 0001 1100 92 0101 1100 156 1001 1100 220 1101 1100
29 0001 1101 93 0101 1101 157 1001 1101 221 1101 1101
30 0001 1110 94 0101 1110 158 1001 1110 222 1101 1110
31 0001 1111 95 0101 1111 159 1001 1111 223 1101 1111
               
32 0010 0000 96 0110 0000 160 1010 0000 224 1110 0000
33 0010 0001 97 0110 0001 161 1010 0001 225 1110 0001
34 0010 0010 98 0110 0010 162 1010 0010 226 1110 0010
35 0010 0011 99 0110 0011 163 1010 0011 227 1110 0011
36 0010 0100 100 0110 0100 164 1010 0100 228 1110 0100
37 0010 0101 101 0110 0101 165 1010 0101 229 1110 0101
38 0010 0110 102 0110 0110 166 1010 0110 230 1110 0110
39 0010 0111 103 0110 0111 167 1010 0111 231 1110 0111
40 0010 1000 104 0110 1000 168 1010 1000 232 1110 1000
41 0010 1001 105 0110 1001 169 1010 1001 233 1110 1001
42 0010 1010 106 0110 1010 170 1010 1010 234 1110 1010
43 0010 1011 107 0110 1011 171 1010 1011 235 1110 1011
44 0010 1100 108 0110 1100 172 1010 1100 236 1110 1100
45 0010 1101 109 0010 1101 173 1010 1101 237 1010 1101
46 0010 1110 110 0110 1110 174 1010 1110 238 1110 1110
47 0010 1111 111 0110 1111 175 1010 1111 239 1110 1111
               
48 0011 0000 112 0111 0000 176 1011 0000 240 1111 0000
49 0011 0001 113 0111 0001 177 1011 0001 241 1111 0001
50 0011 0010 114 0111 0010 178 1011 0010 242 1111 0010
51 0011 0011 115 0111 0011 179 1011 0011 243 1111 0011
52 0011 0100 116 0111 0100 180 1011 0100 244 1111 0100
53 0011 0101 117 0111 0101 181 1011 0101 245 1111 0101
54 0011 0110 118 0111 0110 182 1011 0110 246 1111 0110
55 0011 0111 119 0111 0111 183 1011 0111 247 1111 0111
56 0011 1000 120 0111 1000 184 1011 1000 248 1111 1000
57 0011 1001 121 0111 1001 185 1011 1001 249 1111 1001
58 0011 1010 122 0111 1010 186 1011 1010 250 1111 1010
59 0011 1011 123 0111 1011 187 1011 1011 251 1111 1011
60 0011 1100 124 0111 1100 188 1011 1100 252 1111 1100
61 0011 1101 125 0111 1101 189 1011 1101 253 1111 1101
62 0011 1110 126 0111 1110 190 1011 1110 254 1111 1110
63 0011 1111 127 0111 1111 191 1011 1111 255 1111 1111
Example Question: Which of the following is a Class C IP address?
      A. 10.10.14.118
      B. 135.23.112.57
      C. 191.200.199.199
      D. 204.67.118.54

                          
Correct Answer: D.
Explanation:
IP addresses are written using decimal numbers separated by decimal points. This is called dotted decimal notation of expressing IP addresses. The different classes of IP addresses is as below:
Class
Format 
Leading Bit  pattern
Network address Range   
Maximum  networks
Maximum hosts     
A
N.H.H.H
 0
 0-126
 127
 16,777,214
B
N.N.H.H   
 10
 128-191
 16,384
 65,534
C
N.N.N.H
 110
 192-223
 2,097,152
 254
Network address of all zeros means "This network or segment".
Network address of all 1s means " all networks", same as hexadecimal of all Fs.
Network number 127 is reserved for loopback tests.
Host (Node) address of all zeros mean "This Host (Node)".
Host (Node) address of all 1s mean "all Hosts (Nodes) " on the specified network.
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