difference between dns in windows2000 & windows2003

We can rename or moved the domain name without rebulding in
windows 2003 server,but in windows 2000 server, we can't do
that.

Shadow copy feature available in windows2003 server but not
in windows2000 server.A new tools to recover files.

There are 220 new group polices are added in windows2003
server over windows2000 server.

In windows2000 server support maximum 10 users access shared
folders at a time through network, but windows2003 server no
limitation.

Windows 2003 server includes IIS in it.
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1.Windows 2003 can run 32 and 64 bit both but windows 2000
can run only 32.
2.Windows 2000 support NT 5 and 2003 support NT 6.
3.Kerbors security is high compare to window 2000.

Reverse DNS Delegation

Reverse DNS Delegation

When you register a domain name with a domain registrar, you usually become responsible for that Forward DNS domain. In DNS terms, the domain is delegated to you.

However, you are not also responsible for your reverse records. Your Reverse DNS records are still most likely to be the responsibility of your hosting facility or ISP.

To make changed to your Reverse DNS PTR records, you must contact the company where you get your IP addresses from, usually a hosting facility or an ISP.

Alternatively, your ISP or hosting company may delegate a range of IP addresses to you, in which case you must configure Reverse DNS and PTR records in your DNS server.

what is dns port number

Service	Port
FTP	20,21
SSH	22
telnet	23
SMTP	25
DNS	53
DHCP	67,68
TFTP	69
HTTP	80
POP3	110
NNTP	119
NTP	123
IMAP4	143
LDAP	389
HTTPS	443
IMAPS	993
RADIUS	1812
AIM	5190

what is Reverse lookup

Reverse lookup

In most DNS lookups, clients typically perform a forward lookup, which is a search based on the DNS name of another computer as stored in an address (A) resource record. This type of query expects an IP address as the resource data for the answered response.

DNS also provides a reverse lookup process, enabling clients to use a known IP address during a name query and look up a computer name based on its address. A reverse lookup takes the form of a question, such as "Can you tell me the DNS name of the computer that uses the IP address 192.168.1.20?"

DNS was not originally designed to support this type of query. One problem for supporting the reverse query process is the difference in how the DNS namespace organizes and indexes names and how IP addresses are assigned. If the only method to answer the previous question was to search in all domains in the DNS namespace, a reverse query would take too long and require too much processing to be useful.

To solve this problem, a special domain, the in-addr.arpa domain, was defined in the DNS standards and reserved in the Internet DNS namespace to provide a practical and reliable way to perform reverse queries. To create the reverse namespace, subdomains within the in-addr.arpa domain are formed using the reverse ordering of the numbers in the dotted-decimal notation of IP addresses.

This reversed ordering of the domains for each octet value is needed because, unlike DNS names, when IP addresses are read from left to right, they are interpreted in the opposite manner. When an IP address is read from left to right, it is viewed from its most generalized information (an IP network address) in the first part of the address to the more specific information (an IP host address) contained in the last octets.

For this reason, the order of IP address octets must be reversed when building the in-addr.arpa domain tree. The IP addresses of the DNS in-addr.arpa tree can be delegated to companies as they are assigned a specific or limited set of IP addresses within the Internet-defined address classes.

Finally, the in-addr.arpa domain tree, as built into DNS, requires that an additional resource record (RR) type — the pointer (PTR) RR — be defined. This RR is used to create a mapping in the reverse lookup zone that typically corresponds to a host (A) named RR for the DNS computer name of a host in its forward lookup zone.

Note

•

The in-addr.arpa domain applies for use in all TCP/IP networks that are based on Internet Protocol version 4 (IPv4) addressing. The New Zone Wizard automatically assumes that you are using this domain when creating a new reverse lookup zone. If you are installing DNS and configuring reverse lookup zones for an Internet Protocol version 6 (IPv6) network, you can specify an exact name in the New Zone wizard. This will permit you to create reverse lookup zones in the DNS console that can be used to support IPv6 networks, which uses a different special domain name, the ip6.arpa domain. Additional information is available on IPv6 and DNS, including examples of how to create and use ip6.arpa domain names in Request for Comments (RFC) 3596, "DNS Extensions to support IP version 6." For more information, refer directly to this RFC, which can be obtained from the RFC Editor Web site.

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Example: Reverse query (for IPv4 networks)

The following figure shows an example of a reverse query initiated by a DNS client (host-b) to learn the name of another host (host-a) based on its IP address, 192.168.1.20.

Art Image

The reverse query process as shown in this figure occurs in the following steps:

1.	The client, "host-b", queries the DNS server for a pointer (PTR) RR that maps to the IP address of 192.168.1.20 for "host-a". Because the query is for PTR records, the resolver reverses the address and appends the in-addr.arpa domain to the end of the reverse address. This forms the fully qualified domain name ("20.1.168.192.in-addr.arpa.") for which to be searched in a reverse lookup zone.
2.	Once located, the authoritative DNS server for "20.1.168.192.in-addr.arpa" can respond with the PTR record information. This includes the DNS domain name for "host-a", completing the reverse lookup process.

Keep in mind that if the queried reverse name is not answerable from the DNS server, normal DNS resolution (either recursion or iteration) can be used to locate a DNS server that is authoritative for the reverse lookup zone and that contains the queried name. In this sense, the name resolution process used in a reverse lookup is identical to that of a forward lookup.

what is DNS

Domain Name System (DNS) is one of the industry-standard suite of protocols that comprise TCP/IP. Microsoft Windows Server 2003. DNS is implemented using two software components: the DNS server and the DNS client (or resolver). Both components are run as background service applications.

Network resources are identified by numeric IP addresses, but these IP addresses are difficult for network users to remember. The DNS database contains records that map user-friendly alphanumeric names for network resources to the IP address used by those resources for communication. In this way, DNS acts as a mnemonic device, making network resources easier to remember for network users.

The Windows Server 2003 DNS Server and Client services use the DNS protocol that is included in the TCP/IP protocol suite. DNS is part of the application layer of the TCP/IP reference model.

DNS in TCP/IP

For more information and to view logical diagrams illustrating how DNS fits with other Windows Server 2003 technologies, see “How DNS Works" in this collection.

By default, Windows Server 2003 DNS is used for all name resolution in a Windows Server 2003 network. In the most typical scenario, when a Windows Server 2003 network user specifies the name of a network host or an internet DNS domain name, the DNS Client service running on the Windows Server 2003 computer of the user contacts a DNS server to resolve the name to an IP address.

what is forward lookup zone

A forward lookup zone is a DNS zone in which hostname to IP address relations are stored. When a computer requests the IP address of a specific hostname, the forward lookup zone is queried and the result is returned.

A reverse lookup zone does just the opposite. When a computer requests the hostname of an IP address, the reverse lookup zone is queried and the result is returned.

Also, it is possible to have secondary forward lookup zones when using active directory integrated DNS. The secondary zone won't be ADI, but the primary zone from which it pulls can be. Also, DNS zone can only be Active Directory Integrated if the DNS server on which they reside also happens to be a domain controller. If your dns server isn't a domain controller, the zones aren't ADI, just standard forward lookup zones.

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