Pass4usre Microsoft 70-291 certification engine
latonia | 27 November, 2008 08:06
Identifying the Sources of Risk: It’s Not as Simple as It Seems
Many risk management experts caution that we should look for all sources of risk. They identify the sources of risk as people, processes, and technology. Other experts include things beyond our control, such as your ISP’s lax password policy that could be a risk to the security of your organization’s data. Identifying the sources of risk, however, is not always simple. SY0-101 70-272 70-630
In 1998, a small Midwestern consulting firm’s telephone system was rendered inoperable in the middle of a business day when the system administrator changed the account used to run the service for the software-based Private Branch Exchange (PBX) system. The change was made, in accordance with the PBX system documentation, to facilitate the delivery of voice mail directly to the employees’ mailboxes. However, when the PBX system was brought back on line, the phones were all dead. Fortunately, the administrator was able to determine that the problem could be rectified by granting the new account appropriate permissions on the database. Nowhere in the PBX system documentation was that step listed or even alluded to.
It is easy to see, after a loss occurs, how it happened. Yet if you had been evaluating the risks associated with the PBX, which source of risk would you have identified?
Was the source of the risk people related? The systems administrator has to make changes to systems configuration from time to time—did she make a mistake or proceed without all the information? Did the administrator make a change to the configuration without thinking of the possible consequences? If she had reviewed the process with others, she might have questioned why permissions were not being reassigned.
Was the source of the risk technical? The system might have failed because its configuration was in error. Wouldn’t a better design have warned the administrator that a change in accounts might cause a problem? New error messages in Microsoft Windows Server 2003 and Windows XP Professional seek to warn users and administrators of nonreversible operations, such as password resets, that might damage the ability to access critical data such as encrypted files. 70-297 70-640 mb2-631
Was the source of the risk process related? Should the operational procedures have been required to be tested or at least reviewed before they were implemented? Or, perhaps such a major change should have been made during less critical business hours.
Threats to Security Introduced by Security Maintainability Issues
Any operations design must satisfy maintainability goals, and this is even more important with security design. If security cannot be maintained, it might be eliminated. The following threats to security can result when security designers forget to consider maintainability:
If a security design has a high reliance on people following a written policy that cannot be enforced via technical controls, it is unlikely that adherence to the policy will continue over time.
If a technical control is difficult to maintain, its enforcement might weaken over time. If there is no way, for example, to prevent the introduction of modems into the network and strict restrictions on Internet access are enforced via the local area network (LAN) connection, users might use modems as alternative paths to access the Internet. In doing so, they breach security by avoiding filters, access controls, and logging.
When controls must be renewed and it is difficult to do so, business productivity will be disrupted. Can certificates be automatically reissued before they expire, or must new certificates be manually obtained? Who will manage the intrusion detection systems when the person who received training and cared for the intrusion detection systems for three years leaves the company?
Important Support for security maintainability is important. In Windows Server 2003, functions such as Group Policy can be used to reapply security settings on a periodic basis. Computer and user certificates can be automatically deployed. Security templates can be reapplied to stand-alone systems and used to audit security compliance. 70-294 70-647 70-291
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latonia | 27 November, 2008 07:40
Guidelines for Mitigating the Cost of Security
Follow these guidelines to minimize the cost of security: 70-293 70-431 70-236 70-642
Always insist on a clear and complete statement of the cost that security adds to any project. Whether the cost is prepared by vendors, internal IT staff, management, or the security designer, it must be complete.
Look at security solutions that reduce cost. Are there security technologies suitable for this project that can reduce overall cost and thus improve profitability? An example of such technologies is the use of Secure Sockets Layer (SSL) encryption accelerator cards in e-commerce projects. People rarely doubt the need for secure servers to protect the transmission of sensitive customer or partner financial information during an e-commerce transaction. However, SSL encryption does reduce the number of transactions that can be processed per minute. Slowing the processing of monetary transactions is not a good thing, but removing SSL encryption is not an acceptable solution. SSL-encryption accelerator cards are the answer. Although these cards add cost to a security project, they pay for themselves because they allow the number of possible SSL-encrypted transactions to increase and provide the required care of customer information as it traverses the Internet.
Look for security technologies that, if not employed, absolutely will result in the failure of the project or will result in large, unnecessary expenses. No one today can imagine running an e-mail gateway without antivirus protection. However, it was not long ago that the purchase of such products was seen only as an expense that might be useful. Many organizations learned the hard way that not providing and frequently updating antivirus protection on both the gateway and the end-user machine leads to business interruptions and larger expenses than the cost of providing protection in the first place.
Look for other tangential business drivers that, if not analyzed, can lead to increased expense. For example, confidentiality and integrity—or perhaps the lack of confidentiality and integrity—are becoming increasingly larger legal issues. Ignorance of relevant laws and regulations is not an excuse not to follow them. Potentially large fines and lawsuits can be the result of failure to follow current laws. Another example is that although designing and deploying security can be expensive and require significant expertise, the lack of security can cost even more. The hard costs of the security design—such as costs for equipment, training, and so on—should always be a part of the project cost-benefit analysis. In some cases, it can be shown that adding security reduces the cost of doing business.
Guidelines for Managing Legal Requirements
Follow these guidelines to manage legal requirements: 70-271 770-445 70-237 NS0-201
Have the organization’s legal team review each security design.
Improve the security design team’s awareness of current legal requirements.
Require the security design team to prepare legal compliance as part of its design.
Have a frank discussion with IT-knowledgeable attorneys early in each product or process development cycle.
Testking demo update certification demo download
latonia | 26 November, 2008 08:34
Security templates are text files that store policy settings from the Security node in an Active Directory Group Policy. These text files can be imported and applied to GPOs, altering the settings in the GPO to conform to a particular security standard. Because they are text files, security templates are often far easier to manipulate than GPOs. MB4-641 000-M26 70-448 000-209 MB4-640 352-001 642-524 HP0-M17
Security templates can be edited in two ways. The first is by using the Security Template snap-in of the Microsoft Management Console. This method is the simplest way to edit the templates because it displays them in a form that is similar to that of the Group Policy Editor. Because security templates are stored in text file format, you can also edit security templates by using a text editor such as Notepad. This method is far more complicated and requires detailed knowledge of the security template syntax. Unless there is a compelling reason to do so, use the Security Template snap-in, because editing by using Notepad might lead to inadvertent errors in a template which, when applied, could make a system insecure.
After a security template is created, it must be deployed before it can have any influence on the security configuration of a system. Security templates are generally deployed by importing them into a Group Policy object. Once they have been imported into a Group Policy object, that Group Policy object can then be applied to sites, domains, and organizational units. Security templates can also be deployed by importing them into local Group Policy objects on standalone systems that are not a part of the domain. This can be done by editing the local Group Policy object (gpedit.msc) or by importing the template using the secedit command.
The principles involved in deploying a security template across a domain are similar to the principles involved in deploying Group Policy objects. In general, deployment should be as specific as possible. Grouping target systems into organizational units or sites is far preferable to deploying GPOs with security templates applied at the domain level. This way only the systems that are the targets of these policies will have to process them, and systems for which the policies are not relevant will not be delayed. The more Group Policy settings that are applied within a domain to all machines, the longer those machines take during startup and logon to process all of the policies to reach a final configuration.
One of the advantages to using security templates to configure the security settings in Group Policy objects is that they provide a documented point of reference for determining what went wrong when unexpected results appear. The security configuration and analysis tool can be used to look into the expected results. An administrator can also diagnose where what was planned diverged from what actually happened. One of the most common problems that occurs when security settings are applied is that the rules of Group Policy inheritance are forgotten. Policies applied at the organizational unit level override those applied at the domain level, which in turn override those applied at the site level, which finally override those that are applied locally. This gets even more complicated when policies are applied with the “no override” and “block inheritance” settings. Understanding how these options work is the key to diagnosing problems that occur in the application of security templates. HP0-M23 000-938 000-100 000-960 000-995 190-805 HP0-S16
Pass4sure 156-215.1 free demo download
latonia | 21 November, 2008 09:07
802.1X authentication 70-541 70-299 MB7-517 70-526
Although the early implementations of WEP were woefully inadequate, WEP’s vulnerability can be significantly reduced by using 802.1X authentication. 802.1X enables WEP to regularly change the encryption keys, which dramatically reduces the likelihood that an attacker will be able to gather enough data to identify the shared secret.
802.1X employs an Internet Engineering Task Force (IETF) standard protocol called Extensible Authentication Protocol (EAP) to carry the authentication conversation between the client, the WAP, and a Remote Access Dial-In User Server (RADIUS) service. As part of the 802.1X secure authentication process, the EAP method generates an encryption key that is unique to each client. RADIUS forces the client to generate a new encryption key on a regular basis, which makes it more difficult for an attacker to capture enough traffic to identify a key. This allows existing WEP-capable hardware to be used while minimizing WEP’s vulnerabilities.
PEAP PEAP is typically used to authenticate wireless clients by using a user name and password; EAP-TLS is used to authenticate wireless clients by using public key certificates. Although using a user name and password is not as strong as using public key certificates, because passwords can be stolen or guessed, the resulting encryption is still very strong. When PEAP authentication is used with a RADIUS service that forces encryption keys to change regularly, the resulting WEP encryption is not likely to be compromised in a reasonable amount of time. PEAP’s primary advantage over EAP-TLS is that it is easier to deploy because it does not require you to implement a Public Key Infrastructure (PKI).
The PEAP authentication method has two phases. Phase 1 authenticates the RADIUS server by using the RADIUS server’s public key certificate and then establishes a TLS session to the RADIUS server. Phase 2 requires a second EAP method tunneled inside the PEAP session to authenticate the client to the RADIUS service. This allows PEAP to use a variety of client authentication methods.
This is an important point: PEAP uses two separate types of authentication, one in each authentication phase. The first authentication is handled by PEAP without requiring administrative configuration. You must configure the second authentication protocol, however. Although wireless standards could theoretically support any authentication method, Windows Server 2003 and Windows XP support two by default: Microsoft Challenge Handshake Authentication Protocol version 2 (MS-CHAP v2) and certificates using EAP-TLS tunneled inside PEAP. You will almost always use MS-CHAP v2 with PEAP, however, because you should use EAP-TLS for certificate-based authentication. Certificate-based authentication does not require the additional layer of encryption provided by PEAP.
Security Alert It’s a good thing the MS-CHAP v2 authentication is protected by TLS encryption, because MS-CHAP v2 is indeed susceptible to an offline dictionary attack. An attacker who can capture a successful MS-CHAP v2 exchange can methodically guess passwords until the correct one is determined. It would take a while, but the attacker will eventually get the password.
After the user is successfully authenticated, the authentication server supplies dynamically generated keying material to the WAP. From this keying material, the WAP creates new encryption keys for data protection. 642-811 MB7-515 70-631 156-215.1
Exam Tip If you have a hard time remembering the difference between PEAP and EAP-TLS, you can think of the P in PEAP as standing for password, because you usually use PEAP for password-based authentication, and you use EAP-TLS when client certificates are available.
Pass4sure Microsoft 70-630 practice testing
latonia | 21 November, 2008 08:56
WEP 70-640 70-297 70-630
WEP is a wireless security protocol that helps protect your information by using a security setting, called a shared secret or a shared key, to encrypt network traffic before transmitting it over the airwaves. This helps prevent unauthorized users from accessing the data as it is being transmitted.
Unfortunately, some smart cryptographers found several theoretical ways to discover WEP’s shared secret by analyzing captured traffic. These theoretical weaknesses were quickly implemented in freely available software. The combination of free tools for cracking WEP encryption, the ease of capturing wireless traffic, and the dense proliferation of wireless networks have led WEP to become the most frequently cracked network encryption protocol today.
Security Alert You won’t need to understand the details of the WEP standard for the exam, but it is an interesting study on how not to make an encryption protocol. The most easily exploited weakness of WEP is that many of WEP’s possible initialization vectors (IVs) are cryptographically weak and can expose individual bytes of the WEP key. WEP changes these IVs over time, and an attacker who captures millions of packets will eventually gather enough packets with weak IVs to crack the entire WEP key. Some wireless network adapters intentionally avoid using weak IVs, which makes it much more time-consuming to expose the WEP key. Ask your network adapter vendor what they’ve done to make WEP communications more secure. For more detailed information on WEP’s weaknesses, search for the paper titled “Weaknesses in the Key Scheduling Algorithm of RC4” on the Internet. MB2-631 70-294 70-647
Besides weak cryptography, another factor contributing to WEP’s vulnerability is that WEP is difficult to manage because it doesn’t provide any mechanism for changing the shared secret. On wireless networks with hundreds of hosts configured to use a WAP, it is practically impossible to regularly change the shared secret on all hosts. As a result, the WEP shared secret tends to stay the same indefinitely. This gives attackers sufficient opportunity to crack the shared secret and all the time they need to abuse their ill-gotten network access.
WEP
WEP is a wireless security protocol that helps protect your information by using a security setting, called a shared secret or a shared key, to encrypt network traffic before transmitting it over the airwaves. This helps prevent unauthorized users from accessing the data as it is being transmitted.
Unfortunately, some smart cryptographers found several theoretical ways to discover WEP’s shared secret by analyzing captured traffic. These theoretical weaknesses were quickly implemented in freely available software. The combination of free tools for cracking WEP encryption, the ease of capturing wireless traffic, and the dense proliferation of wireless networks have led WEP to become the most frequently cracked network encryption protocol today.
Security Alert You won’t need to understand the details of the WEP standard for the exam, but it is an interesting study on how not to make an encryption protocol. The most easily exploited weakness of WEP is that many of WEP’s possible initialization vectors (IVs) are cryptographically weak and can expose individual bytes of the WEP key. WEP changes these IVs over time, and an attacker who captures millions of packets will eventually gather enough packets with weak IVs to crack the entire WEP key. Some wireless network adapters intentionally avoid using weak IVs, which makes it much more time-consuming to expose the WEP key. Ask your network adapter vendor what they’ve done to make WEP communications more secure. For more detailed information on WEP’s weaknesses, search for the paper titled “Weaknesses in the Key Scheduling Algorithm of RC4” on the Internet.
Besides weak cryptography, another factor contributing to WEP’s vulnerability is that WEP is difficult to manage because it doesn’t provide any mechanism for changing the shared secret. On wireless networks with hundreds of hosts configured to use a WAP, it is practically impossible to regularly change the shared secret on all hosts. As a result, the WEP shared secret tends to stay the same indefinitely. This gives attackers sufficient opportunity to crack the shared secret and all the time they need to abuse their ill-gotten network access. 70-270 SY0-101 70-291
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latonia | 20 November, 2008 09:41
Public Key Infrastructure 156-215.1 MB7-515 642-811 70-526
Public key encryption wouldn't be any easier than shared key encryption if everyone had to manually exchange public keys. That's why we use a PKI-to make the process of managing and exchanging public keys simpler. A PKI is a set of policies, standards, and software that manages certificates and public and private keys. A PKI consists of a set of digital certificates, certification authorities (CAs), and tools that can be used to authenticate users and computers and to verify transactions. In order to place the PKI implementation provided by Windows Server 2003 in the proper context, this section provides a general overview of the components that make up a PKI.
See Also The data formats and network communications used by a PKI are (mostly) standardized. For detailed, but dry, information about PKI standards, refer to RFC 2459.
Certificates
A public key certificate, referred to in this chapter as simply a certificate, is a tool for using public key encryption for authentication and encryption. Certificates are issued and signed by a CA, and any user or application that examines the certificate can safely assume that the CA did indeed issue the certificate. If you trust the CA to do a good job of authenticating users before handing out certificates, and you believe that the CA protects the privacy of its certificates and keys, you can trust that a certificate holder is who he or she claims to be.
Certificates can be issued for a variety of functions, including Web user authentication, Web server authentication, secure e-mail, encryption of network communications, and code signing. CAs even use certificates to identify themselves, create other certificates, and establish a certification hierarchy between other CAs. If the Windows Server 2003 enterprise CA is used in an organization, clients can use certificates to log on to the domain.
Certification authorities
A CA is an entity trusted to issue certificates to an individual, a computer, or a service. A CA accepts a certificate request, verifies the requester's information according to the policies of the CA and the type of certificate being requested, generates a certificate, and then uses its private key to digitally sign the certificate. A CA can be a public third party, such as VeriSign, or it can be internal to an organization. For example, you might choose to use Windows Server 2003 Certificate Services to generate certificates for users and computers in your Active Directory directory service domain. Each CA can have distinct proof-of-identity requirements for certificate requesters, such as a domain account, an employee badge, a driver's license, a notarized request, or a physical address.
Registration is the process by which subjects make themselves known to a CA. Registration can be accomplished automatically during the certificate enrollment process, or it can be accomplished by a trusted entity such as a smart card enrollment station. Certificate enrollment is the procedure that a user follows to request a certificate from a CA. The certificate request provides identity information to the CA, and the information the user provides becomes part of the issued certificate.
Certificate life cycle MB7-517 70-299 70-541
Certificates cannot be used forever; that would give an attacker too much time to identify the corresponding private key. Certificates have a predefined life cycle and expire at the end of this life cycle. You, as the security administrator, maintain control over the certificate. You can extend the lifetime of a certificate by renewing it, or end the usefulness of a certificate before the expiration date by revoking it.
A number of factors influence the length you will choose for a certificate lifetime, such as the type of certificate, the security requirements of your organization, the standard practices in your industry, and government regulations. In general, longer keys support longer certificate lifetimes and key lifetimes. Longer lifetimes reduce administrative labor, which reduces costs.
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latonia | 19 November, 2008 09:10
Considerations for Evaluating Your Environment 70-431 70-646 70-236
When establishing an authentication strategy for your organization, you must become familiar with your current environment, including the structure of your organization; the users, computers, and services in your organization that require authentication; and the applications and services that are in use. This will help you to understand the requirements and constraints of your organization.
When evaluating your environment, identify the following:
The number of domain controllers in your organization. Ensure that there are enough domain controllers to support client logon requests and authentication requests while meeting your redundancy requirements. A sufficient number of domain controllers will ensure that a large volume of authentication requests will not result in authentication failures, even if a domain controller is offline because of hardware or network failures.
The type of network connectivity between site locations in your organization. Ensure that clients in remote sites are connected well enough to authenticate to domain controllers located in main sites. If connectivity is an issue, consider installing domain controllers in sites that might have logon problems because of slow or unreliable links. 642-415 642-373 70-642
Planning Everyone is always concerned about whether they have enough bandwidth, but it’s latency that’s more likely to cause authentication problems across wide area network links. Authentication requires very little bandwidth. However, packets must go back and forth across the link several times. If latency causes a significant delay for each round trip, authentication will seem slow.
The number of certification authorities (CAs) that are available in your organization and their locations. Ensure that you have enough CAs to support the anticipated number of certificate requests.
Guidelines for Creating a Strong Password Policy
Encryption limits your vulnerability to having user credentials intercepted and misused. Specifically, password encryption is designed to be extremely difficult for unauthorized users to decrypt. Ideally, when a strong password is used, it should take an attacker months, years, or decades to identify the unencrypted password after the attacker captures the encrypted or hashed password. During that time, the password should have been changed—making the unencrypted password now useless.
In contrast, weak passwords can be identified in a matter of hours or days, even when they have been encrypted. Encryption cannot protect against passwords that are easily guessed, because weak passwords are vulnerable to dictionary attacks. Dictionary attacks encrypt a list of common passwords, and compare each possibility with the captured cyphertext. If the password appears in the password dictionary, the attacker will identify the password quickly. You can defend against this vulnerability by implementing a strong password policy.
Off the Record The best way to understand how effective dictionary attacks are is to grab a password cracking tool from the Internet and experiment with it on a test machine. I can’t point you to a specific tool, but they’re not hard to find. 70-271 70-445 70-237
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latonia | 19 November, 2008 09:10
Considerations for Evaluating Your Environment 70-431 70-646 70-236
When establishing an authentication strategy for your organization, you must become familiar with your current environment, including the structure of your organization; the users, computers, and services in your organization that require authentication; and the applications and services that are in use. This will help you to understand the requirements and constraints of your organization.
When evaluating your environment, identify the following:
The number of domain controllers in your organization. Ensure that there are enough domain controllers to support client logon requests and authentication requests while meeting your redundancy requirements. A sufficient number of domain controllers will ensure that a large volume of authentication requests will not result in authentication failures, even if a domain controller is offline because of hardware or network failures.
The type of network connectivity between site locations in your organization. Ensure that clients in remote sites are connected well enough to authenticate to domain controllers located in main sites. If connectivity is an issue, consider installing domain controllers in sites that might have logon problems because of slow or unreliable links. 642-415 642-373 70-642
Planning Everyone is always concerned about whether they have enough bandwidth, but it’s latency that’s more likely to cause authentication problems across wide area network links. Authentication requires very little bandwidth. However, packets must go back and forth across the link several times. If latency causes a significant delay for each round trip, authentication will seem slow.
The number of certification authorities (CAs) that are available in your organization and their locations. Ensure that you have enough CAs to support the anticipated number of certificate requests.
Guidelines for Creating a Strong Password Policy
Encryption limits your vulnerability to having user credentials intercepted and misused. Specifically, password encryption is designed to be extremely difficult for unauthorized users to decrypt. Ideally, when a strong password is used, it should take an attacker months, years, or decades to identify the unencrypted password after the attacker captures the encrypted or hashed password. During that time, the password should have been changed—making the unencrypted password now useless.
In contrast, weak passwords can be identified in a matter of hours or days, even when they have been encrypted. Encryption cannot protect against passwords that are easily guessed, because weak passwords are vulnerable to dictionary attacks. Dictionary attacks encrypt a list of common passwords, and compare each possibility with the captured cyphertext. If the password appears in the password dictionary, the attacker will identify the password quickly. You can defend against this vulnerability by implementing a strong password policy.
Off the Record The best way to understand how effective dictionary attacks are is to grab a password cracking tool from the Internet and experiment with it on a test machine. I can’t point you to a specific tool, but they’re not hard to find. 70-271 70-445 70-237
Pass4sure Cisco 642-642 exam information
latonia | 18 November, 2008 08:56
Analyzing the Existing DNS Implementation 350-001 156-915.65 642-642
Unless you are tasked with building a network infrastructure from the ground up, most
network administrators have to understand and work with DNS infrastructures that are
already in place. This lesson includes an overview of the DNS components and discusses
some of the terminology you will need to understand before you can design
and implement a DNS strategy for your company.
The first step in analyzing a company’s network infrastructure is to perform an analysis
of the company itself. As discussed in Chapter 2, understanding how a company works
and how its information flows lays a critical foundation for the rest of your network
design. In this lesson, you learn to gather information regarding the DNS infrastructure
that is in place.
DNS Overview
Most human beings do not like working with numbers or having to memorize Internet
Protocol (IP) addresses to connect to a resource on the network. It’s a lot easier to
memorize www.microsoft.com as an address than 172.16.45.67. When a Fully Qualified
Domain Name (FQDN) such as www.microsoft.com is entered by a user on a network,
there must be a method or component that takes that name and resolves it to an IP
number. DNS does exactly that. As you saw in Chapter 1, this name resolution process
can be quite involved. In this section, you will look at the various components that
make it all happen.
Components of DNS
Because you have already gathered all of the information pertaining to the physical
locations of the various departments and divisions of your company, and have created
network diagrams of the present infrastructure, you are almost ready to analyze the
DNS structure of the company. The diagrams you have created illustrate where all
servers, routers, switches, and so on are located. This information, combined with the
locations and total amount of hosts, subnets, and routers, will help you to understand
how the present DNS infrastructure is configured.
DNS Zones
A zone is defined as a contiguous portion of a DNS tree that is administered as a
separate entity by a DNS server. It can store information about one or more domains.
A zone contains resource records associated with a particular domain. For example,
Contoso’s DNS namespace for the domain contoso.com may have originally been
configured as a single zone, but as the domain grows and many subdomains are
added—such as ftp.contoso.com, www.contoso.com, marketing.contoso.com, and so
on—you can assign different zones to each subdomain.
Windows Server 2003 allows you to choose between several different zone types (as
shown in Figure 6-1).
Primary zone Contains a local copy of the DNS zone where resource records
are created and updated. VCP-310 640-802 190-848
Secondary zone A read-only copy of a DNS zone. It can be updated only through
replication from a primary zone, and is used for redundancy and load balancing.
Active Directory integrated zone A primary zone stored in Active Directory.
Stub zone A copy of a zone that contains only the resource records needed to
identify authoritative DNS servers, thereby simplifying DNS administration and
improving name resolution.
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latonia | 18 November, 2008 07:07
Designing a WINS Server Placement Strategy 156-215.1 70-643 NS0-201
Your goal, when designing a WINS strategy for your network infrastructure, is to have
the WINS service available to client workstations when they need it. Availability is at
risk when there is only one WINS server configured to support a large number of users.
If that server should fail, all of the users will now need to resolve NetBIOS names using
one of the other methods covered earlier: Lmhosts files or broadcasts. In situations in
which a slow link exists between two subnets, it is highly recommended that a WINS
server be placed in both subnets to maximize performance of client name-resolution
requests.
Just as much thought had to go into deciding where to place your DNS servers, you
can see that placing your WINS servers in the right location can also influence performance.
For example, a remote site that has several thousand users may warrant placing
a WINS server there to avoid the prospect of sending the traffic generated from name
registrations over a 128Kb frame relay connection. Once again, your network topology
diagrams are critical in making such decisions.
Fault Tolerance 70-237 70-445 70-271
When designing your WINS infrastructure, you should consider the possibility of something
going wrong—because it usually does. Having only one WINS server on a routed
network, regardless of how small the network is, can create problems if a WINS server
unexpectedly crashes due to hardware failure or is inadvertently shut down for maintenance
by a junior network administrator who is not aware that the server is running
WINS. By placing secondary WINS servers throughout your network infrastructure, you
reduce the effects of one server being unavailable for your clients. If cost is a factor
preventing you from implementing this, Lmhosts files configured with #PRE-tag entries
for critical servers are a good way of ensuring that clients can access network resources
in the event of a downed router or WINS server.
Non-Routed Networks
On a small LAN with one WINS server, you will not see as much of a problem with a
WINS server crashing as you would in a routed network. Users on the LAN would be
able to access all network resources located on the LAN using broadcast requests.
However, they may see a noticeable degredation in performance on low-bandwidth
networks.
Routed Networks
On a routed network, where users on a remote segment rely on the WINS server across
the router to perform NetBIOS name resolution, a WINS server that is made unavailable
could prevent users from doing their jobs. For example, all applications that relied
on NetBIOS name resolution would not function. Access to servers and printers may
not be possible for all remote users. Another possible problem could arise if the router
connecting to the subnet containing the WINS server failed. In designing your WINS
infrastructure, all of these scenarios must be considered. 70-642 642-373 642-415
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latonia | 17 November, 2008 07:06
Creating DataSet Objects NS0-201 70-643 156-215.1
DataSet objects are available in the System.Data namespace and are used as an in-memory cache of the data being used in your application. DataSet objects contain DataTable objects that can be related with DataRelation objects much like the structure of a relational database.
DataSet Objects
Datasets are objects that you use to temporarily store the data that is used in your application. There are basically two distinct kinds of DataSet objects: typed, and untyped. Untyped DataSets are the standard generic instances of the DataSet class where you manually build up the DataSet definition (schema) by creating DataTable objects (untyped DataTables) and adding them to the Tables collection in the DataSet. You can access untyped DataTable and DataColumn objects through their collection indices. Typed DataSet objects derive their schema from an .xsd file and contain explicitly typed collections (such as a specific CustomersTable object).
There are three distinct ways to create DataSet objects in Visual Studio:
Declare a new DataSet object programmatically in the code editor, which results in an empty DataSet that requires creating DataTable and optional DataRelation objects to be added to the DataSet.
Use design-time tools such as the DataSet Designer and the Data Source Configuration Wizard which assists in the creation of typed DataSet objects by stepping you through the process of selecting or creating a data connection and then allowing you to select database objects available from that connection to build up a typed DataSet and have most, if not all, of the necessary code generated for you.
Drag a DataSet object from the Toolbox onto a form and use the Table and Column
Collection editors to build up the schema of your DataSet. 642-444 70-631 MB7-515
Merging DataSet Contents
You can take the contents from one DataSet (the source dataset) and merge it with the contents of another DataSet (the target dataset) using the DataSet.Merge method.
When merging datasets, the actual data is combined depending on whether a similar record exists in the DataSet into which it will be merged. For example, if you merge two datasets that both contain a record with the same primary key, the values in the target DataSet will be overwritten with the new values in the source DataSet. You can control this behavior and restrict changes from being made in the target DataSet by passing in a true or false value to the PreserveChanges flag in the Merge method. In addition to merging the actual data, when you merge two DataSets that have tables with differing schema, you can pass an optional MissingSchemaAction parameter to the Merge method that controls the behavior of the merge when the source DataSet has objects that are not currently in the target DataSet. The following are valid values for the MissingSchemaAction parameter:
Add (default) All schema items in the source DataSet are added to the target DataSet and populated.
AddWithKey All schema items and primary key settings are added to the target DataSet.
Error An exception will be thrown when the schemas in the source and target DataSets do not match.
Ignore All schema inconsistencies between the source and target DataSets are ignored.
In the following code example, the contents of the OldSalesDataSet are merged into the contents of the SalesHistoryDataSet. The PreserveChanges parameter is set to True and any schema differences will be ignored. 642-811 642-061 70-526
Pass4sure Microsoft 70-649 exam guides
latonia | 17 November, 2008 06:00
Performing Bulk Copy Operations 640-801 HP0-145 70-646
This lesson describes how to copy large amounts of data quickly, using the SqlBulkCopy object provided by the System.Data.SqlClient namespace and the BULK INSERT SQL statement in SQL Server. In addition to performing an individual bulk copy operation, you will also learn how to perform a set of bulk copy operations wrapped within a transaction.
Why Perform Bulk Copies?
Copying large amounts of data from one database table to another (or from a file to a database table) can take a lot of time and resources if you simply create an application that reads individual rows out of the original data source and then insert the individual rows into the destination data source. To accomplish the task of moving many records (or entire tables) of data, use the .NET Framework and SQL Server bulk copy features, which perform the transfer of the bulk copies more efficiently than transferring individual records.
Lab: Bulk Copying
In this lab you will bulk copy data from one table to another.
Creating Tables to Copy Data into
To demonstrate how to perform a bulk copy operation, you need tables to copy data into. A quick way to create the tables is to use Server Explorer and the Visual Database Tools to do some cutting and pasting! Use the following steps to create CustomerHistory and OrderHistory tables, which you will use to bulk copy the Customer and Order table data into. 70-291 1D0-510 MB6-508
1.In Server Explorer, expand the Tables node for the Northwind database.
2.Right-click the Customers table and select Open Table Definition.
3.Select the first row by clicking the box with the key icon.
4.Press Ctrl+A to select all the rows.
5.Press Ctrl+C to copy them to the clipboard.
6.Right-click the Tables node in Server Explorer and select Add New Table.
7.Select the empty row (not a cell but the entire row) and press Ctrl+V to paste the table definition into the row.
8.Select only the CustomerID row. Right-click the CustomerID row and select Set Primary Key.
9.Save the table and name it CustomerHistory.
10.Repeat these steps with the Orders table, set the OrderID as the primary key, and save the table with the name OrderHistory.
Lesson Summary
Bulk copying provides an efficient way to copy large amounts of data.
The SqlBulkCopy object provides a .NET Framework class to perform bulk copy operations in your application.
The SQL BULK INSERT statement provides a way to perform bulk copy operations using the resources in SQL Server.
Bulk copy operations can be performed from within a transaction.
Lesson Review 190-802 70-290 70-649
The following questions are intended to reinforce key information presented in this lesson. The questions are also available on the companion CD if you prefer to review them in electronic form.
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latonia | 13 November, 2008 09:02
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latonia | 13 November, 2008 08:37
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Testking Microsfot certification 70-291 update practice infomation
latonia | 23 October, 2008 07:36
Chapter 1 Introduction to Active Directory and Network Infrastructure
Data delivery in the transport layer is controlled by two protocols:
Transmission Control Protocol (TCP) TCP is referred to as a connectionoriented
protocol because a connection must be established between two XK0-002 642-973 sy0-101
computers before any data is transferred. It is also referred to as a reliable protocol
because it checks up on the delivery of data to a remote computer by requiring
that an acknowledgment be returned. If the remote computer does not return an
acknowledgment within a specified period of time, the source computer
retransmits the data. Most applications use TCP to transmit data.
User Datagram Protocol (UDP) UDP is a connectionless service in that it does
not establish a connection before transmitting data. UDP also does not require an
acknowledgment of receipt. This provides faster data delivery than TCP but does
not offer the capability to retransmit data that is not acknowledged. UDP is often
used by applications sending very small amounts of data and by applications that
stream media over a network, where retransmittal of data would not be useful.
A port is associated with applications that use either the TCP or UDP protocols; these
ports are referred to as TCP ports and UDP ports. A port can have any number between
0 and 65,535. The port numbers from 0 to 1,023 are reserved for common applications.
Referred to as the well-known port numbers, these are under the control of the Internet
Assigned Numbers Authority (IANA). Ports from 1024 through 49151 are also under the
control of IANA and are referred to as Registered Ports; these are used for less wellknown
applications. Ports between 49152 and 65535 220-602 646-588 70-270 are referred to as dynamic or
private ports. You’ll learn more about port numbers in Chapter 7.
Internet Layer
The Internet layer is responsible for addressing, packaging, and routing the data that is
handed down to it from the transport layer. There are four core protocols in this layer:
Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Control Message
Protocol (ICMP), and Internet Group Management Protocol (IGMP).
Internet Protocol IP is a connectionless, and therefore unreliable, protocol that is
primarily responsible for addressing packets and routing them between networked
computers. Although IP always attempts to deliver a packet, a packet may be lost,
corrupted, delivered out of sequence, duplicated, or delayed. IP does not attempt to
recover from these types of errors by requesting retransmission of the data.
Acknowledging the delivery of packets and recovering lost packets is the responsibility
of a higher-layer protocol, such as TCP, or of the application itself.
IP also assigns a Time to Live (TTL) value to each packet, which specifies the maximum
length of time that the packet can travel on the network before being discarded. The
TTL is measured in seconds, which represent the maximum time a packet can survive on
a network. Every instance of IP that processes a packet decrements the TTL by at least
one. Any instance of IP that examines a packet with a TTL of zero discards the packet.
Address Resolution Protocol ARP is responsible 70-284 70-294 70-647 for mapping IP addresses to the
hardware addresses (or MAC addresses) of the network adapters of computers on the
network. When IP readies a packet for transmission to a remote computer, it does so
using that computer’s IP address. However, the actual network cards (and other network
interfaces) on a network transfer data using long hardware addresses that ensure
each network interface on a network is uniquely identified.
In the Windows Server 2003 implementation of ARP, ARP translates between IP
addresses and hardware addresses and maintains a table of mappings known as the
ARP cache. This table is built dynamically. When ARP receives a request to translate an
IP address, it checks for the address in its table. If the address is found, ARP returns the
address to the requesting software. If the address is not found in the table, ARP broadcasts
a packet to the local subnet; this packet contains the IP address for which the
hardware address is needed. If a receiving host identifies the IP address as its own, it
responds by sending its hardware address back to the requesting host. The response is
then stored in the ARP cache.
Internet Control Message Protocol ICMP provides error reporting and traffic control
messaging. With ICMP, computers and routers that use IP communication can report
errors and exchange limited control and status information. For example, if IP is unable
to deliver a packet to a destination computer,1Y0-259 MB2-633 70-291 ICMP sends a Destination Unreachable
message to the source computer.
Internet Group Messaging Protocol The Internet Group Membership Protocol (IGMP)
is used by hosts to report multicast group membership to adjacent routers. Multicasting
allows one host to send content to multiple other hosts simultaneously. Examples
would be streaming high-bandwidth media to multiple computers, updating software
on a number of computers at once, and some types of distribution lists. Typically, a
group of computers becomes part of a multicast group membership so that they can be
sent multicast messages.
Network Access Layer
The network access layer is responsible for placing data on the network medium and
receiving data off the network medium. This layer contains physical devices such as
network cables and network adapters. This layer does not contain the type of softwarebased
protocols that are included in the other three layers, but it does contain such
protocols as Ethernet and Asynchronous Transfer Mode (ATM), 642-845 1z0-042 XK0-002 which define how data
is transmitted on the network.