Server_4

Server interview questions and answers

Windows System/Desktop support

• What is the reason for hanging a pc? Explain
• What is the reason for slowing pc? Explain
• How to speed up pc while it was slow?
• If a pc is in no display why?
• How to set virtual memory in 2000?
• Beep sound will be long, why?
• TCP/IP protocol Explain?
• What is color-coding for cross cabling and Straight Cabling?
• How to change computer name in windows 2000 or XP?
• How to create a folder in NTFS?
• How is set NTFS security for a folder?
• What is ghost? Explain?
• How to use Ghost? What is advantage?
• What is Ms-Outlook and Outlook Express? And what is the difference?
• What is the page file?
• What is the default location of Ms-Outlook data file?
• What is port no of SMTP, TCP/IP, and POP3?
• How to get backup in MS-Outlook?

Explanation Section

What is a server? What is a client?

A server is a computer that makes its resources available to the network and responds to the commands of a client. The server’s shared resources can be files (a file server); printers (a print server); processing power (an application server); and just about any computer resource.

A client is a computer that uses the resources made available by a server. The client must have sufficient processing power on its own to run applications that interact with the resources on the server.

How is a network organized?

With Windows NT, peer-to-peer networks are organized into workgroups.

A server-based network is organized as a domain.

Workgroup.

A workgroup is a logical collection of computers identified by a unique name. Members of the workgroup can see and access resources shared by other computers within the group. Each computer in the workgroup manages its own security.

Domain

Unlike a workgroup, a domain is managed by a central server called a ‘Primary Domain Controller’ or PDC that maintains a single user accounts database. That database can be shared with other servers called ‘Backup Domain Controllers’ (BDCs). The domain controllers provide logon validation to ensure that domain user accounts and security policies are enforced within the domain. Permissions and rights within the domain are typically assigned to groups and then users are assigned to the groups. Thus, a user’s ability to access resources on the network depends primarily on his or her group memberships. There can be more than one domain on a network. Users from one domain can access the resources of another domain if the appropriate trust relationships have been established.

NAME RESOLUTION

NETBIOS

Netbios Names also known as computer names - For resolving Computer Name to IP address, NETBIOS protocol is heavily relied upon. Before TCP/IP was introduced.

The user specifies 15 characters of a NetBIOS name on a computer to assign a unique computer Name To resolve NETBIOS Names Netbios Cache memory / Broad casting / LM Host File / WINS / WINS Proxy / WINS Static.

Netbios Cache memory -- This cache memory has recently resolved name nbstat – c. To remove the entry in netbios or LM Host file == nbstat –R. Resolved name will be in Netbios cache memory for certain period till the service is stopped.

LMHOST File: By default device like router will not allow broadcast from one network to other network. This is accomplished by LM Hostfile. Open it in note pad and add the server or host or ip address to show in the network. This will resolve with reduced traffic. LMHOST File contains a list of IP address with matching NetBIOS names for all of the computers on remote subnets . Disadvantage of LM Host file is entries should be made manually

WINS: Windows Internet naming service; To avoid going through the procedures i.e., Netbios, Broadcast, LM Host file for the name resolution and to add the systems in the netwok. If the Network is large we go for WINS.

WINS (Windows Internet Naming Service)

WINS provides local name resolution between IP address and NetBIOS names.

When a WINS Client request the IP address for a computer name, WINS Server retrieves the IP address from its database and returns to the WINS client. Most networks should be configured with more than one WINS server to provide load balancing in case of primary WINS server fails. When multiple WINS servers are installed, they can be configured to exchange their databases with each other.

Benefit of WINS

1. Reduced broadcast network traffic

2. No need for an LMHOSTS file

3. Dynamic name registration

4. No duplicate computer names

5. No specific need for a DNS server

Limitation of WINS

The performance is degraded when many clients are registered in its database. And second replication is not that much good as DNS. Though 2000 has eliminated WINS, most network will still require the use of it for win 95,98 and NT.

DNS (DOMAIN NAMING SERVICE)

It is used to resolve host names into IP address When the Internet was small, file called HOSTS that contained mappings of every other host on the Internet and its IP address. However, as the Internet grew, the process of updating HOSTS files on every system became increasingly unmanageable. Hence DNS was introduced to solve this problem.

How DNS Works?

DNS uses a client/server model in which the DNS server maintains a static database of domain names mapped to IP addresses. The DNS client, known as the resolver, perform queries against the DNS servers. DNS resolves domain names to IP address using these steps .

To resolve domain names to an IP address with DNS

1.A client (or “resolver”) passes its request to its local name server. For example, the URL term www.idgbooks.com typed into Internet Explorer is passed to the DNS server identified in the client TCP/IP configuration. This DNS server is known as the local name server.

2.If, as often happens, the local name server is unable to resolve the request, other name servers are queried so that the resolver may be satisfied.

3.If all else fails, the request is passed to more and more, higher-level name servers until the query resolution process starts with far-right term (for instance, com) or at the top of the DNS tree with root name servers.

Zones: DNS database files are called Zones. It administers the portion of DNS.

In order to prevent failed server we make multiple servers for a zone. They are :-

Primary Name server: It is responsible for maintaining the primary copy of DNS records. All changes to a zone, such as adding a domain or host are performed at Primary Name Server.

Secondary Name Server: The purpose of Secondary server is to provide Fault tolerance i.e. in case of primary server unavailable. It reduces the traffic Otherwise that would go to the primary server.

Zone Transfer - Secondary Name server gets the data for its zones from another name server across the network in a process called Zone Transfer. It is a file copy procedure that replicates the contents of the DNS database from the primary name server to a secondary name server. A zone transfer occurs immediately when a secondary name server starts up.

Master Name Server: This is used to replicate the DNS data between the Primary and secondary servers. Generally primary servers as master server. Due to performance reasons the master server is responsible for propagating the changes to the DNS databases to all secondary servers within a particular zone.

Caching only Server: A catching-only DNS server may be used at sites that have slow connectivity to DNS servers at other sites.

DNS Resource Records.

A database file or “zone file” is a file of resource records (RRs). It is used to indicate the type of data stored by each record. Different types of records occur in zone files, and you may elect to query for only one type of record.

Several types of resource records can appear. They are

A (Address) Records.- It is the heart of DNS database providing mapping between host names to IP address.

MX (Mail Exchange) Records: Internet mail systems such as Send mail can work with DNS to discover which hosts are functioning as mail servers for a domain.

PTR (Pointer) Records- Used for reverse lookup operations. That are used to return the host name when a DNS client has only the IP address.

SOA (Start of authority)- Defines number of general operational parameters for DNS servers such as Name server, Serial Number, Refresh, Retry, TTL.

SRV (Service) Records :. Windows 2000 uses SRV Record to Locate

A Domain Controller in domain or in a forest.

A Domain controller in the same site as a client computer

The Domain Controller configured as Global Catalog Server

Interoperability of DNS with DHCP AND WINS

DHCP

DHCP is a method of dynamically assigning IP address to hosts on the network for a predetermined period called a lease DHCP avoids the need for static mapping of addresses to computers. Only few hosts (such as name resolution servers and default gateways) must have fixed IP address. As TCP/IP requires a lot of manual configuration which includes TCP/IP address, Subnet mask, Default gateway, DNS servers, DNS Domain name , Wins servers, it leads to troublesome management. DHCP works automatically assigning TCP/IP address information to client computers when they are first connected to the network. Client initializes a broadcast and sent to the DHCP Server and server generates a IP address from its database of valid assignments . Generally IP address are limited resources on most networks, DHCP servers assign a lease duration to each IP address they assign to clients. This lease will last for 5 days. Clients need to renew their IP else IP will be retired. The pool of TCP /IP address that are available for assignment to clients is called the DHCP SCOPE.

Scope consists of :-

A Valid range of unique pool of IP address and subnet mask (A definite set of IP address within the pool that are not available for lease such as network address, default gateways or name resolution servers such as DNS , WINS Servers) A Valid Subnet mask for that pool

Note:

When we install DHCP Server on the Services tab in the network applet, the DHCP Manager is automatically added to the Administrative Tool

When a computer leaves the network and rejoins, it does not automatically lose its lease, but broadcasts a request for an IP address and finishes its lease

If a client has a static Ip address then this will override any scope settings.

Only windows operating system can be a DHCP client and Win- Server machines can DHCP Server

Integrating DNS AND DHCP

In order to reduce the manual administration of DNS entries for client computers, win 2000’s DNS can automatically create Address (A) records for host based on DHCP information.. When Dynamic updates are enabled, the clients updates the A record as soon as they receive the IP address and the DHCP server updates the client’s PTR record. Win 95, 98, NT does not support Dynamic updates, therefore DHCP server itself must update the DNS A and PTR records.

DYNAMIC DNS

Integrating WINS and DNS together and using a best-of-breed name resolution tool. That is exactly what Windows 2000 Server will do with the introduction of Dynamic DNS. Dynamic DNS, based on RFC 2136, is a means for providing dynamic updates of zone data on a zone’s primary server when an authorized server requests an update.
Clearly, Dynamic DNS has several advantages over old-fashioned DNS. One such advantage is that updates are not limited to manual edits of a zone’s resource records.