HOW DNS SUFFIX SERVER CONNECT TO THE NETWORK

DNS resolves fully qualified domain names to IP addresses, the DNS server wasn't much help when users and scripts tried to connect to file servers or the Web server by host name alone. By default, Windows clients will append their domain name to a host name when they try and query DNS. However, when other domains exist on the network, a host will not automatically append the names of the other domains to any DNS name resolution requests.
For example, suppose a computer named intel is a member of the domain samirreports.blogspot.com. If a user tried to connect to http://server1, the computer would query DNS for the IP address of samirreports.blogspot.com. If server1 was a member of blue.com and thus no record for server1 existed in the samirreports.blogspot.com forward lookup zone on the DNS server, the client request would time out.

At this point its could solve this problem the ugly way and just add an A record for server1 to the samirreports.blogspot.com forward lookup zone on the DNS server, but this is not recommended. each server should have an A record in each domain's forward lookup zone on the DNS server. Next, you need to configure the DNS suffix search order on each system on the network. This allows a host to try multiple fully qualified domain name combinations when it tries to resolve a name using DNS.
For example, if the domain name blue.com was added to bsod's DNS suffix search order, bsod would first attempt to resolve the host name server1 as samirreports.blogspot.com. It would then query DNS for samirreports.blogspot.com. Once it received a reply from DNS, bsod would then connect to server1.
A large network, you probably be instanane if you tried to use the above procedures to manually configure the DNS suffix search order on each workstation. Microsoft seemed to think so to, and with Windows Server 2003 can now configure DNS suffix search order with a GPO. If you create a new GPO or edit an existing GPO on a Windows 2003 domain controller, you'll see that you can set the DNS suffix search order by navigating to Computer Configuration Administrative Templates Network DNS Client.
Then double-click on the DNS Suffix Search List object. Once you click the Enabled radio button you'll be able to add domain names (separated by commas) to the DNS Suffixes field. If you need further help with this setting, click the Explain tab.
If you're not running a Windows 2003 domain, you could still change the DNS suffix search order via a VBScript. Microsoft has posted a sample script that works on Windows 98/NT/2000/XP/2003 at the TechNet Script Repository.
Finally, if you want to see the DNS query process from a DNS client that is configured to search for names across multiple domains, you can enable debug logging on the DNS server. To do this, follow these steps:
1. In the DNS MMC, right-click the DNS server object and select Properties.
2. Check the Log Packets for Debugging check box.
3. Leave all other default options checked and click OK. (No, you really don't need every default, but it's easier for me to document this way!)
DNS suffix search order on a Windows system by following these steps:
1. Access the properties of the network interface you wish to configure.
2. Double-click on "Internet Protocol (TCP/IP)."
3. In the Internet Protocol (TCP/IP) Properties dialog box, click the Advanced button.
4. Click the DNS tab in the Advanced TCP/IP Settings dialog box.
5. Click the "Append these DNS suffixes (in order)" radio button.
6. Now click the Add button to add DNS suffixes to the connection.
7. In the TCP/IP Domain Suffix dialog box, enter the name of the first domain name to append to any DNS search (samirreports.blogspot.com).
8. Repeat steps 6-7 for each additional domain.
9. When finished, click OK to close the Advanced TCP/IP Settings dialog box.
10. Click OK to close the Internet Protocol (TCP/IP) Properties dialog box.
Click OK to close the network connection's Properties dialog box.
DNS client and query a name of a server (by host name only) that is in the second domain in the DNS suffix search list. Then can open the %systemroot%\system32\dns\dns.log file on the DNS server to see the query results. Following my earlier example, after configuring samirreports.blogspot.com first and blue .com second in the DNS suffix search order of my Windows XP client, I then ran the command nslookup server1 and received the following response from the DNS server:
Name: server1.redmondmag.comAddress: 192.168.0.7
After receiving a response from the DNS, I then opened the dns.log file on the DNS server and scrolled the log file down toward the bottom (time of the query). Here are the results specific to my query:

13:09:09 704 PACKET UDP Rcv 192.168.0.120 0009 Q [0001 D NOERROR] (7)server1(6)mcpmag(3)com(0)
13:09:09 704 PACKET UDP Snd 192.168.0.120 0009 R Q [8385 A DR NXDOMAIN] (7)server1(6)mcpmag(3)com(0)
13:09:09 704 PACKET UDP Rcv 192.168.0.120 000a Q [0001 D NOERROR] (7)server1(10)redmondmag(3)com(0)
13:09:09 704 PACKET UDP Snd 192.168.0.120 000a R Q [8385 A DR NOERROR] (7)server1(10)redmondmag(3)com(0)
In the first line listed, the DNS client is requesting to resolve the name samirreports.blogspot.com. In the second line, the server is responding to the client with NXDomain (non-existent domain). The client then requests to resolve server1.blue.com and the DNS server replies to the client with the correct A record. Since DNS logging is pretty verbose, I would only keep it enabled long enough to perform your test. After that I would disable it.
So, properly configuring the DNS suffix search order can make a world of difference with name resolution on your network. Also, with a tuned DNS infrastructure, life without WINS is possible. Sometimes I think WINS is like crack. We were given it with Windows NT and many became addicted. In the end, it can break the addiction.If there was a 7 step program for WINS addiction, properly configuring.

HOW TO USE DNS CLIENT SETTINGS IN COMPUTER

DNS configuration involves the following tasks when configuring TCP/IP properties for each computer: For example: Setting a DNS computer or host name for each computer., in the fully qualified domain name (FQDN) Samirreports.blogspot.com., the DNS computer name is the leftmost label samirreports. Setting a primary DNS suffix for the computer, which is placed after the computer or host name to form the FQDN. Setting a list of DNS servers for clients to use when resolving DNS names, such as a preferred DNS server.
Setting computer names
When setting computer names for DNS, it is useful to think of the name as the leftmost portion of a fully qualified domain name (FQDN).Example: in samirreports.blogspot.com.. samirreports is the computer name. ITS can configure all Windows DNS clients with a computer name based on any of the standard supported characters defined in Request for Comments (RFC) 1123, "Requirements for Internet Hosts -- Application and Support. If you are supporting both NetBIOS and DNS namespaces on your network, it can use a different computer name within each namespace. It is recommended that wherever possible, however, you try to use computer names that are 15 char requirements outlined above acters or less and that you follow the RFC 1123 naming. By default, the leftmost label in the FQDN for clients equals the NetBIOS computer name, unless this label is 16 or more characters, which is the maximum for NetBIOS names. When the computer name exceeds the maximum length for NetBIOS, the NetBIOS computer name is truncated based on the full label that is specified.
Before configuring computers with varying DNS and NetBIOS name.
consider the following implications and their related issues for your deployment.
If you have an investment in using NetBIOS names to support legacy networking technology, it is recommended that you revise NetBIOS computer names used on your network to prepare for migration to a standard DNS-only environment. This prepares your network well for long-term growth and interoperability with future naming requirements. For example, if you use the same computer name for both
NetBIOS and DNS resolution,
Consider converting any special characters such as the underscore (_) in your current NetBIOS names that do not comply with DNS naming standards. While these characters are permitted in NetBIOS names, they are more often incompatible with traditional DNS host naming requirements and most existing DNS resolver client software.
Notes
Although the use of the underscore (_) in DNS host names or in host resource records has been traditionally prohibited by DNS standards, the use of underscores in service-related names--such as those used for service locator (SRV) resource records--has been proposed to avoid naming collisions in the Internet DNS namespace. For more information.
if(typeof(IsPrinterFriendly) != "undefined")
{
var l = "/WindowsServer/en/library/60601f25-a8b3-4316-851f-8e0cc99673ec1033.mspx";
var nl;
var c = l.charAt(0);
var o = document.getElementById("ELC");
switch (c){
case "/":
nl=(" [http://" + document.domain + l + "]");
break
case "#":
nl=("");
break
default:
nl=" [" + l + "]"
}
if(o != null) o.innerHTML = nl;
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In addition to DNS standard naming conventions, Windows Server 2003 DNS supports the use of extended ASCII and Unicode characters. However, since most resolver software written for other platforms (such as UNIX) is based on the Internet DNS standards, this enhanced character support can be used only in private networks with computers running Windows 2000 or Windows Server 2003 DNS.
The initial setup of DNS and TCP/IP displays a warning to suggest a standard DNS name if a nonstandard DNS name is entered.
By default, computers and servers use DNS to resolve any name that is greater than 15 characters in length. If the name is less than or equal to 15characters, then both NetBIOS and DNS name resolution can be attempted and used to resolve the name.

Setting domain names
The domain name is used with the client computer name to form the fully qualified domain name (FQDN), known also as the full computer name. In general, the DNS domain name is the remainder of the FQDN that is not used as the unique host name for the computer.
For example, the DNS domain name used for a client computer could be the following: If the FQDN, or Full computer name, is
samirreports.blogspot.com.
DNS domain names have two variations--a DNS name and a NetBIOS name. The full computer name (a fully qualified DNS name) is used during querying and location of named resources on your network. For earlier version clients, the NetBIOS name is used to locate various types of NetBIOS services that are shared on your network.
Example that shows the need for both NetBIOS and DNS names is the Net Logon service. In Windows Server 2003 DNS, the Net Logon service on a domain controller registers its service (SRV) resource records on a DNS server. For Windows NT Server 4.0 and earlier versions, domain controllers register a DomainName entry in WINS to perform the same registration and to advertise their availability for providing authentication service to the network.
When a client computer is started on the network, it uses the DNS resolver to query a DNS server for SRV records for its configured domain name. This query is used to locate domain controllers and provide logon authentication for accessing network resources. A client or a domain controller on the network optionally uses the NetBIOS resolver service to query WINS servers, attempting to locate DomainName [1C] entries to complete the logon process.

Your DNS domain names should follow the same standards and recommended practices that apply to DNS computer naming described in the previous section. In general, acceptable naming conventions for domain names include the use of letters A through Z, numerals 0 through 9, and the hyphen (-). The use of the period (.) in a domain name is always used to separate the discrete parts of a domain name, commonly known as labels. Each label corresponds to an additional level defined in the DNS namespace tree.
For most computers, the primary DNS suffix configured for the computer can be the same as its Active Directory domain name, although the two values can also be different.
By default, the primary DNS suffix portion of a computer's FQDN must be the same as the name of the Active Directory domain where the computer is located. To allow different primary DNS suffixes, a domain administrator may create a restricted list of allowed.
suffixes by creating the msDS-AllowedDNSSuffixes attribute in the domain object container. This attribute is created and managed by the domain administrator using Active Directory Service Interfaces or the Lightweight Directory Access Protocol (LDAP).

For computers running Windows XP, the DNS server list is used by clients only to resolve DNS names. When clients send dynamic updates, such as when they change their DNS domain name or a configured IP address, they might contact these servers or other DNS servers as needed to update their DNS resource records.
if(typeof(IsPrinterFriendly) != "undefined")
{
var l = "/WindowsServer/en/library/e760737e-9e55-458d-b5ed-a1ae9e04819e1033.mspx";
var nl;
var c = l.charAt(0);
var o = document.getElementById("EWE");
switch (c){
case "/":
nl=(" [http://" + document.domain + l + "]");
break
case "#":
nl=("");
break
default:
nl=" [" + l + "]"
}
if(o != null) o.innerHTML = nl;
}
.
By default, the DNS client on Windows XP does not attempt dynamic update over a Remote Access Service (RAS) or virtual private network connection. To modify this configuration, you can modify the advanced TCP/IP settings of the particular network connection or modify the registry.

D E S I G N P R I N C I P L E S OF L I N U X

IN Linux design principles are any other traditional,nonmicrokernel UNIX implementation.
It is a multiuser,multitasking system with a full set of UNIX-compatible tools.Linux file system address to traditional UNIX semantics and the standared UNIX networking model is implemented Fully.The internal details of Linux design have been influenced heavily by the history of this operating systems development.
Although Linux runs on a wide variety of platforms,it was developed exclusively on PC architecture.A great deal of that early development was carried out by individual
enthustasts, rather than by well-funded development or research facilities.so the start Linux attemped to squeeze as much functionally as possible from limited resources.Linux can run happily on a multiprocessor machine with hundreds of megabytes of main memory and many gigabytes of diskspace.Is capable of operatingsyatem usually in under 4 MB of ram.

AS,the PCs become more powerful and as memory and hard-disk becomes cheaper.Linux kernel grew to implement more UNIX functionality.speed of efficiency are still important design goals,but much of the recent and current work on Linux has cocentrated on a third major design goal.One of the prices paid for the diversity of UNIX implementations currently available is that source code written for the flavour may not necessarily compile or run correctly on another.Even when the same system calls are represent on two different UNIX system,they do not behavily exactly same way.The POSIX standareds comprise a set of specifications of different aspects of operating-system behaviour.There are POSIX documents for common operating system functionally and for extensions such as process threads and realtime operations.Linux is designed to be compliment with thr relevant POSIX commands.

Because,it represents standareds interfaces to both the programer and the userr.Linux presents few surprises to anybody familiar with UNIX.The section on the programer interfaces and user interfaces of BSD apply equally well to Linux.However , the Linux programing interfaces address to SVR4 UNIX semantics,rather than to BSD semantics in places where the two behaviours are significantly different.

Many other standareds exists in the UNIX world,but full certification Linux against them is sometimes slowed because they are often available only for a fee,and the expense involved

in certifying an operating systems compliance with most standareds issubstantial. However ,supporting a wide base of applications is important of any operating system,so implementation of standards is a major goal for Linux devewlopment,. n addition

to basic POSIX standared,Linux currently supports the POSIX threading extensions.

IN Linux kernel forms the core of the Linux project.It is desigined to composed entirely of code written from the scratch specially for the Linux project.and much of supportig of softeare that makes of the Linux system is not exclusively to Linux but is common to
Number of UNIX like operating systems.

How can a computer be connected safely to an untrustewrthy network

One solution the use of a firwell to separate trusted and untrusted system.A firwell is a computer appliance or router that sits between the trusted and untrusted.A network firwell limits network acess between the two security domains and monitors and logs all connection. It can also limit connection best on source or destination adress ,source or destination port,or direction of the connection.For instance,web server use HTTP to communicate with web browsers. A firwell may also only HTTP to pass form all host outside the firwell to the web sever with in the firwell.The morris internet worm used the finger protocol to break in to computers,so finger would not be allowed to pass,
A network firwell can separate a network into multiple firewall.
A common implementation has the internet as the untrusted domains. A common implementation has the internet as the untrusted domain.A semi trusted and semi-secure network called demilitarized domain.
A firwall itself must be secure and attack-proof,otherwise its ability to secure connections can be compromised.Firwell do not prevent attacks that tunnel,or travel within protocols or connections that the firwell allows. A buffer-overflow attack to a web-server will not be stopped by the firwell. Because the HTTP connection that house the attack,likewise, denial-of-service attacks can affect firwell as much as any other mchines.Another vulnerability of firwell is spooling, in wich an unauthorized host pretends to be an authorized host by meeting some authorization criterion. If a firewell rule allows a connection from a host and identifies that host by its IP address,then another host could send packets using that same address and be allowed through the firwell.
IN addition to the most common network firewalls,there are other,never kinds of firewalls,each with its pros and cons. A personal firewall is a software layer either included with the operating system or added as an application.Rather than limiting communication between the security domains,it limits communication to a given host. A user could add a personal firewall to her PC is connected.An application proxy firewall understands the protocols that applications speak across the network.Firewall understands the protocols that application speak across the network.SMTP is used for mail transfer.An application proxy accepts a connection just as an SMTP server would and then initiates a connection to the orginal destination SMTP server.It can monitor the traffic as it forwards the message, watching for and disabling illegal commands,attempts to exploit bugs. Some firewalls are designed for one specific protocol. An XML firewall, has the specific purpose of analyzing XML traffic and blocking disallowed or malformed XML. System call firewall sit between application and the kernel, monitoring system-call execution in Solaris 10, the “least privilege” feature implements a list of more than fifty system calls that process may or may not allowed to make. A process that does not need to spawn other processes can have that ability taken away for instance.