DNS 2

DNS Round Robin

DNS Round Robin is used to provide more than one IP address to a single hostname.

Each IP address represents a different physical host, and requests will be sent to each of the host in a rotation order.

Reverse NAME Resolution

Sometimes a computer needs to convert an IP address to DNS name. This conversion process is known as reverse name resolution.

The developers of the DNS created a special domain called in-addr.arpa that is specially designed for reverse name resolution.

ZONE TYPES

In windows 2003 supports 3 zones

ü  Primary zone

ü  Secondary zone

ü  Stub zone

Primary Zone:

A primary zone contains the master copy of the zone database. The database is stored in the stored in the Active Directory database.

Secondary Zone:

A secondary zone a duplicate of a primary zone on another server contains a backup copy of the primary master zone database file stored as an identical text file on the local drive. You cannot modify the resource records in a secondary zone manually you can only update them by replicating the primary master zone database file using a process called a zone transfer. You should always create at least one secondary zone from each file based primary zone in your name space to provide fault tolerance and load balance the DNS traffic load.

Stub Zone:

A stub zone is a copy of a primary zone that contains SOA and NS resource records plus the HOST (A) resource records that identify the authoritative servers for the zone

Using Active Directory Integrated Zones?

When you are running the DNS server Service on a computer that is an Active Directory domain controller and you select the zone in active directory check box when creating a zone using the new zone wizard the server does not create a zone database file instead it stores the DNS resource records for the zone in the Active Directory database.

Aging and Scavenging:

The process that can be used by window server 2003 DNS to clean up the DNS to clean up the DNS database when resource records no longer required by default it is disabled.

How to verify SRV Records?

Verifying SRV records with NSLOOKUP.

CMD > NSLOOKUP

LS –T SRV domain

LS –T A Domain

WINS – Windows Internet Name Service?

It converts NETBIOS name to IP Addresses.

DNS server converts Host name to IP address.

NetBIOS name is 16 characters

15 character – system name

1 character – service name (DNS, DHCP, DC)

Command to check a system’s NetBIOS Name

Nbtstat – N

Ipconfig –all

WINS server uses LMHOST file which contains all systems NetBIOS name and its IP addresses.

Path – C:\windows\system32\drivers\etc\lmhost.sam

When a new system is added in the network, the LMHost file should be manually updated by the system administrator. It should be created in all systems.

But DNS server is using Dynamic DNS method, when a new system is added it will update host name and IP address automatically.

What is DDNS and why do I need it?

Dynamic DNS allows servers to dynamically update and create records in DNS.

NetBIOS name max length?

The NetBIOS naming convention allows for 16 characters in a NetBIOS name.

Microsoft however limits NetBIOS names to 15 characters and uses the 16 character as a NetBIOS suffix. The NetBIOS is used by Microsoft Networking software to identify functionality on the registered device.

Windows NT is using NetBIOS? True or false details?

Yes because Microsoft networking services running on Windows NT –based computer are identified by using NetBIOS names.

Windows 2000 supports NetBIOS or not?

Yes using WINS it allows a NetBIOS name to be converted to an IP address. Therefore computers using WINS must be using NBT (NetBIOS over TCP/IP). The purpose of WINS is to allow NetBIOS name to be converted to an IP address. Therefore using wins must be using NBT (NetBIOS over TCP/IP).

What is a Zone?

Zone is collection of records.

Types of zones

Forward lookup zone (Name to IP)

 (A to PTR)

Reverse lookup zone (IP to Name)

 (PTR to A)

Zone types

Active directory integrated

Primary zone

(Which store their zone information in a writable text file on the name Server?)

Secondary zone

(Which store their zone information in a read-only text file on the name server?)

Is there any option in windows 2000 stub zone?

NO, stub zone is introduced on windows 2003 server

Net BIOS Name:

The naming mechanism that was used to refer to a computer or domain in earlier versions of windows. It consists of a 15-character name and a sixteenth character that references a service. It usually matches the DNS name.

DNS Records short notes

Host A: A record resolves form a hostname to IP address.

Pointer (PTR): PTR records resolve from an IP address to a hostname.

Start of Authority (SOA): SOA resource record specifies the information required for replication.

Service Record (SRV): A SRV records resolves from a service name to a hostname and port.

Name Server (NS): NS record resolves from a domain name to hostname.

Mail Exchange (MX): it indicates the presence of a SMTP email server.

Your network contains of a single active directory domain named contoso.com. You have a server named server1 that runs custom network applications. Server1 has the following IP address:

192.168.15.10

192.168.15.11

You need to ensure that a client computer resolves server1.contoso.com to only the 192.168.15.11 IP address. What should you do from the computer?

Edit the hosts file.

Differences between the HOSTS and LMHOSTS files in Windows NT.

In Windows NT, the HOSTS file is for TCP/IP utilities and the LMHOSTS file is for LAN manager NET utilities. If you cannot ping another computer (using friendly name), check the hosts file. If you cannot NET VIEW a server using only the tcp/ip protocol, check the LMHOSTS file.

Hosts file

The hosts file is a common way to resolve a host name to an ip address through a locally stored text file that contains ip-address-to-host-name mappings. On most unix-based computers, this file is /etc/hosts. On windows based computers, this file is the host file in the systemroot\system32\drivers\etc folder.

The following describes the attributes of the host file for windows.

1)     A single entry consists of an IP (IPV4 or IPV6) address and one or more host names.

2)     The hosts file is dynamically loaded into the DNS client resolver cache, which windows sockets applications use to resolve a host name to an ip address on both local and remote subnets.

3)     When you create entries in the hosts file and save it, its contents are automatically loaded into the DNS client resolver cache.

4)     The hosts file can be edited with any text editor.

5)     Each host name is limited to 255 characters

6)     Entries in the hosts file for windows based computers are not case sensitive.

The advantage of using a hosts file is that users can customize it for themselves. Each user can create whatever entries they want, including easy-to-remember nicknames for frequently access resources. However the individual maintenance required for the hosts file does not scale well to storing large numbers of FQDN mappings or reflecting changes to ip address for servers and network resources. The solution for the large-scale storage and maintenance of FQDN mappings is DNS. The solution for the maintenance of FQDN mappings for changing IP address is DNS dynamic update.

Not LMHOSTS file.

The lmhosts file is a local text file that maps IP addresses to NetBios names of remote servers with which you want to communicate over the TCP/IP protocol. Windows recognizes names instead of IP addresses for network requests and name discovery process is used to correctly route network requests with tcp/ip. Because the name discovery process is generally not routed by an ip router, the lmhosts file allows windows machines to communicate using tcp/ip across a subnet.

1)     LMHOSTS contains IP addresses to “NetBIOS over TCP/IP” name translations.

2)     LMHOSTS is only used by the NBT (NetBIOS over TCP/IP) interface.

3)     LMHOSTS file contains some valuable additions to the LAN manager and windows for workgroups LMHOSTS file, such as the ability to support routed domain logon validation.

4)     LMHOSTS contains static information about TCP/IP addresses , but using logon scripts and or the replicator service, the “master” file can be distributed transparently across all stations.

5)     By default the lmhosts file should be located in the directory %systemroor%\system32\drivers\etc (using c:\winnt\system32\drivers\etc)…