by: Manbeer Singh
Home networks are becoming more common. People want to be able to share a single broadband Internet connection to several computers in the house. There are many different devices that you can use to make up your home network. If you have never heard network terminology device names like router, hub, etc may seem confusing.
The purpose of most of these devices is to control how the network passes around information. This information is sent in the form of "packets". I will refer to the term packet several times in this article. It simply means the data that the network is transporting. I will now explain the purpose of the major components of a home network.
What is a Hub
A hub is a device that has several Ethernet ports on the back of the device. One of these ports will likely be labeled “Uplink”. This port allows you to connect multiple hubs together, if you run out of ports on your hub. If you do not have an uplink port on your hub, the hub cannot be easily extended if you run out of ports.
A hub is a device that attaches multiple computers on an Ethernet network. If you have a number different computers that you want to connect together, you could connect each to the hub. Any packet that is sent out by any computer on the network will immediately be transmitted to the other computers. Each computer will determine if the packet was really intended for it, and filter out packets that were intended for other computers.
You really should not use a hub in a modern home network. You should always use a switch in place of a hub. Switches will be discussed in the next section.
What is a Switch
A switch is a device that has several Ethernet ports on the back of the device. One of these ports will likely be labeled “Uplink”. This port allows you to connect multiple switches together, if you run out of ports on your switch. If you do not have an uplink port on your switch, the switch cannot be easily extended if you run out of ports.
A switch serves the same function as a hub. It allows you to connect multiple computers together, so that they can exchange packets. However, a switch is much more efficient than a hub. A switch will only send Ethernet packets to the computer that the packet was intended for. Because of this you should always use a switch in place of a hub.
What is a Router
A router is a device that has several Ethernet ports on the back of the device. One of the connectors will be labeled WAN. You should connect the WAN port to the Ethernet connection on a broadband source, such as a cable or DSL modem. The other ports on the router can be connected other computers or switches/hubs that will share the WAN connection.
Routers allow you to share your broadband connection with multiple computers in your house. Rather than connecting your computer directly into your cable or DSL modem you connect the router to the cable or DSL modem. Now any computer that you connect to the router will have access to the Internet.
If you run out of ports on your router you can always connect an additional switch to the router. To connect a switch to a router simply connects the switch’s "uplink" port to one of the routers Ethernet ports. Of course, don’t connect to the router’s WAN port. The WAN port should only be connected to something such as a cable or DSL router.
Some routers come with additional features installed. Most routers also include a firewall. Firewalls are discussed in the next section. Some routers will also include a wireless access point (WAP). The WAP allows you to use wireless devices, such as wireless laptops, with the Internet.
What is a Firewall
A firewall controls traffic flow between your network and the Internet. A firewall can be either hardware or software. Windows XP SP2 or higher includes a software firewall. A hardware firewall is included with most routers.
A firewall is a very good idea. It can protect you from inbound virus attempts. By inbound virus attempt I mean other computers that will connect to your computer and attempt to infect your computer. You do not want to run a computer directly connected to the Internet, without a firewall. There are just too many other computers out there that can connect and infect you without you even noticing.
What is a Network Attached Storage (NAS)
A network attached storage device is a device that allows a hard drive to be shared across the network. This hard drive is NOT attached to any of your computers. It is simply made available by the NAS. This can be a convent way to add a hard drive that can be accessed by several computers on your network. The other common way to add a network hard drive is to simply share a folder on one of your computers. However, with the NAS, you do not need to keep one of your computers on at all times.
There are two types of NAS commonly available. The first type comes with a build in hard drive. The second accepts a USB or Fire wire external hard drive. The advantage to using a USB or Fire wire hard drive is that you can upgrade the hard drive if it ever were to become too small.
What is a Print Server
Just like you can buy a device to allow you to share a hard drive, you can do the same with a printer. A print server connects directly to your printer. Your printer is then shared to all of your computers on the network. This is convent because you do not need to leave the printer hooked to a computer, which must be turned on to print.
Conclusions
As you can see there are many different components. Perhaps the final component that I ave yet to mention is the cable. These components are connected together with CAT5 Ethernet cable.
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Understanding the Components of a Home Network
5 Tips to Organize your Server Room in 2008
by: Marcos Garza
If you are looking to get your server room organized in 2008, there are a few key steps to keep in mind while you are going through the process. Your server room houses valuable information for your business and the safety and security of your equipment should be of top concern. In addition, the equipment that you choose should be efficient and safe for long term use.
1. Choose the Appropriately Sized Rack
As you are looking to organize your server room, the most logical place to start is by choosing new server racks. Select server racks with sufficient internal space to house all of your current equipment and room to accommodate future expansion. Having extra space is a must in your server room for expansion as well as unplanned additional equipment purchases. Some obvious things to check as well include determining that you have enough space to move the new servers in and that you have the proper floor space to maneuver around the equipment and that there is enough space in between the equipment to allow for safety spacing. When you are installing the equipment, be sure to install it according to the included instructions so that you do not have any future problems.
2. Include your New Server Room in your Security Strategy
Security, especially with vital information, is always important for a business to consider. As you are organizing your server room, be sure that any changes or additions fit into your overall business security plan. You may want to consider purchasing server racks that have locking doors, minimizing personnel access to the room and using monitor devices within the room for added protection. In addition, newer technology allows you to monitor the environment of the server room at all times. Temperature changes, water leaks, electrical circuit issues and other issues can change unknowingly, causing potential damage to your server room. With the addition of this technology, you will be able to act quickly to resolve any issues in order to protect your valuable equipment.
3. Customize your Server Rack Design
Once you have decided on a manufacturer for your server racks, most will allow for customization. Consider the addition or modification of the shelving, top or side panels, mounting rails and the feet to create a server room that matches all of your business needs and the space that you are utilizing as your server room.
4. Evaluate your Power Technology
Power technology is constantly updated, providing you with various options for your power strip. You have several choices to consider including rack mount power strips, remote power products, Three-phase power technology and standard power strips. Consider your space, the number of outlets that you will need, each plug’s requirements and any redundancy requirements when you are choosing the power technology for your server room.
5. Ensure your Safety with a Cooling Strategy
The heat that each unit gives off varies, making the cooling needs within your server room vary as well. Evaluate all of your requirements and the available cooling strategies to ensure the overall safety of the equipment, environment and company when making your selections.
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Cisco CCNA, CCENT, CCNP, And CompTIA Questions: HSRP, OSPF Cost, Route Summarization, And More!
by: Chris Bryant, CCIE #12933
Let's test your knowledge of important CCNA, CCENT, CCNP, and Network+ exam topics!
CCNA Certification:
The term used for an OSPF path metric is ____________ .
Extra credit: What formula does OSPF use to calculate that metric?
Answer: OSPF's metric is referred to as cost, and the calculation is 100,000,000 / interface speed in bps.
Cisco CCENT / CompTIA Network+ Question:
Which of the following do TCP and UDP headers have in common?
A. sequence number
B. source port
C. source IP address
D. window
E. destination port
F. destination IP address
G. ACK bit
H. reset bit
Answer: B, E. In addition to the source port and destination port numbers, the UDP and TCP headers also have a checksum field in common.
CCNP Certification / BSCI Exam:
In ISIS, what is the most efficient point of a network at which to perform route summarization?
A. An L1 router.
B. An L2 router.
C. An L1/L2 router.
D. A DIS router.
Answer: C. L1/L2 routers are area boundary routers in ISIS, and this is the most efficient point at which to configure route summarization
CCNP Certification / BCMSN Exam:
Short answer: An HSRP router is the primary router and it has a priority of 100. Another router comes online in the same group and it has a priority of 107. Does the new router become the primary? If so, why? If not, what additional configuration is needed to make it the primary?
Answer. By default, the new router with the higher priority will not become the primary router. To allow a router with a higher priority to take over the role of HSRP primary from an existing and normally functioning primary, the preempt option must be configured on the router with the higher priority.
Let's use a two-router HSRP deployment as an example. R2 is the standby, R3 is the primary ("active"), and both have an HSRP priority of 100. Raising R2's priority to 150 does not automatically make it the primary, as shown below.
R2(config)#interface ethernet0
R2(config-if)#standby 5 priority 150
R2#show standby
Ethernet0 - Group 5
Local state is Standby, priority 150
Hellotime 4 sec, holdtime 12 sec Next hello sent in 0.896
Virtual IP address is 172.12.23.10 configured
Active router is 172.12.23.3, priority 100 expires in 8.072
Standby router is local 1 state changes, last state change 00:14:24
R2 now has a higher priority, but R3 is still the active router. R2 will not take over as the HSRP primary until R3 goes down - OR the preempt option is configured on R2.
R2(config-if)#standby 5 priority 150 preempt
1d11h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Standby -> Active
R2#show standby
Ethernet0 - Group 5
Local state is Active, priority 150, may preempt
Hellotime 4 sec, holdtime 12 sec Next hello sent in 1.844
Virtual IP address is 172.12.23.10 configured
Active router is local
Standby router is 172.12.23.3 expires in 10.204
Virtual mac address is 0000.0c07.ac05 2 state changes, last state change 00:00:13
That's enough for today! Look for more free Cisco and CompTIA certification exam questions on this website soon! A+ certification and Microsoft Vista certification practice questions are on the way as well!
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CCNA, CCENT, Network+, And Security+ Practice Questions: TCP, UDP, Smurf Attacks, And More!
by: Chris Bryant, CCIE #12933
Let’s test your knowledge of UDP, TCP, smurf attacks, EIGRP, and more with these questions designed to help you prepare for success on your CCENT, CCNA, CCNP, Network+, and Security+ certification exams!
CCENT Certification / Network+ Certification:
Which of the following protocols runs on both UDP and TCP?
A. DHCP
B. SNMP
C. DNS
D. ARP
E. Inverse ARP
Answer: C. DNS runs on port 53, both on TCP and UDP.
Security+ Certification:
Briefly define the term "smurf attack". (Not too briefly, though!)
Answer: Basically, a smurf attack involves sends ICMP Echo packets (pings) with the intended victim's IP address specified as the source of the Echo packets. This transmission takes the form of a directed broadcast, which means that quite a few hosts can receive it - and then respond with ICMP Echo Replies, which will all be sent to the intended victim.
CCNA Exam:
R1 and R3 are directly connected at their respective Serial1 interfaces via a DTE/DCE cable. What command will tell you whether the interface is connected to the DTE or DCE end of the cable?
Answer: Run show controller serial 1 on either router - the DTE / DCE information is near the top of the output.
CCNP Certification / BSCI Exam:
DUAL has discovered four possible paths to a remote network, with the following metrics: PathA, 1500. PathB, 1500. PathC, 2600. PathD, 3100. What command will allow EIGRP to use the first three paths without using the fourth?
Answer: variance 2 would do the job. Any path with a metric of 3000 or lower will be utilized; setting it to 3 would bring PathD into the equation.
CCNP Certification / BCMSN Exam:
What is the main purpose of IEEE 802.3ac?
Answer: The IEEE 802.3ac standard allows the maximum frame length to be extended to 1522 bytes, which means the dot1q 4-byte header doesn't cause problems in transmission.
CCNP Certification / ONT Exam:
Which queueing strategy gives priority to interactive, low-bandwidth communications by default?
Answer: Weighted Fair Queueing (WFQ) gives priority to interactive, low-bandwidth conversations, and then splits the remaining bandwidth fairly among the remaining conversations.
Look for a new set of Cisco and CompTIA certification exam questions soon!
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How to Configure Windows Server as a Ntp Server
Computer time synchronisation is highly important in modern computer networks, precision and time synchronization is critical in many applications, particularly time sensitive transactions. Just imagine buying an airline seat only to be told at the airport that the ticket was sold twice because it was purchased afterwards on a computer that had a slower clock!
Modern computers do have internal clocks called Real Time Clock chips (RTC) that provide time and date information. These chips are battery backed so that even during power outages, they can maintain time but personal computers are not designed to be perfect clocks. Their design has been optimized for mass production and low-cost rather than maintaining accurate time.
For many applications, this is can be quite adequate, although, quite often machines need time to be synchronised with other PC's on a network and when computers are out of sync with each other problems can arise such as sharing network files or in some environments even fraud!
Microsoft Windows (2000 and above) has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server. It can be configured to both synchronise a network using the internal clock or an external time source.
Note: Microsoft strongly recommends that you configure a time server with a hardware source rather than from the internet where there is no authentication.
To configure Windows Time service to use the internal hardware clock, first check that w32time is located in the system services list in the registry, to check:
Click Start, Run then type regedit then click ok.
Locate and then click the following registry entry:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Time
It is highly recommended that you back up the registry as serious problems may occur if you modify the registry incorrectly, modifications to the registry are done at your own risk.
Note: the following instructions are based on Windows 2000 other versions of Windows may differ.
To begin configuration for an internal clock, click on the following subkey:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters
In the right pane, right-click ReliableTimeSource, then click Modify.
In Edit DWORD Value, type 1 in the Value Data box, then click OK
Exit Registry Editor
To restart the Windows Time Service click Start, Run (or alternatively use the Command Prompt facility).
Type: net stop w32time && net start w32time
Then press enter.
To reset the local computers’ time, type the following on all computers except for the time server which must not be synchronised with itself:
w32tm –s
To configure the Windows Time service to use an external time source, click Start, Run and type regedit then click OK.
Locate the following subkey:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters
In the right pane, right-click Type then click Modify, in edit Value type NTP in the Value data box then click OK.
Now in the right pane, right click ReliableTimeSource, then click Modify.
In the Edit DWORD Value box, under Value Data, type 0, then click OK.
Right-click NtpServer in the right pane then click Modify.
In Edit Value, type the Domain Name System (DNS), each DNS must be unique.
Now click Ok.
For Windows 2000 Service Pack 4 only, set the time correction settings to do this locate:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters
In the right pane, right-click MaxAllowedClockErrInSecs, then Modify in the Edit DWORD Value box, , type a time in seconds max number of seconds difference between the local clock and the time received from the NTP server in order to be considered a valid new time.
Click OK.
To set the poll intervals locate:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters
In the right pane, right-click Period, then click Modify.
In the Edit DWORD Value box, under Value Data, type 24 then OK
Exit Registry Editor
Click Start, then Run then type the following and press Enter:
Net stop w32time && net start w32time
To reset the local computers’ time, type the following on all computers except for the time server which must not be synchronised with itself:
Network Time Protocol (NTP) is an Internet protocol used for the transfer of accurate time, providing time information along so that a precise time can be obtained
To enable the Network Time Protocol; NTPserver, locate and click:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpServer
In the right pane, right-click Enabled, then click Modify.
In the Edit DWord Value box, type 1 under Value data, then click OK.
Now go back and click on
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer
In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0x1 to the end of each DNS name otherwise changes will not take effect.
Now click Ok.
Locate and click the following
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClientSpecialPollInterval
In the right pane, right-click SpecialPollInterval, then click Modify.
In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.
To configure the time correction settings, locate:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig
In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.
Now go back and click:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig
In the right pane, right-click MaxNegPhaseCorrection, then Modify.
In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour)
Exit Registry Editor
Now to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:
net stop w32time && net start w32time
And on each computer, other than the time server, type:
W32tm/ -s
And that’s it your time server should be now up and running.
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