What is Global Catlog Server

The Global Catalog server is the domain controller that stores a full copy of all objects in its host domain. It also stores a partial copy of all objects in all other domains within the forest.

The Global Catalog (GC) is an important component in Active Directory because it serves as the central information store of the Active Directory objects located in domains, and forests. Because the GC maintains a list of the Active Directory objects in domains and forests, without actually including all information on the objects; and it is used when users search for Active Directory objects or for specific attributes of an object; the GC improves network performance and provides maximum accessibility to Active Directory objects.

Types of DNS Zones

Dns zones

primary zone,
 read/write copy
stored in txt file(easy to backup and recover)
primary zone must available to make changes.

secondry zone,
read only copy
can be copie of primary , secondary, AD integrated.


AD integrated zone.
only available on DC.
All D.C. have a read/write copy of the zone.
high availability and redundancy (Because DNS in AD, so if AD is down another AD still there so DNS always available)
dis Adv: DNS Zone data not stored as txt file. so harder to restore.
ADV: replicate DNS data with AD, so ur DNS data stored in all Domains. so DNS Zone data is very secure.


Stub Zone:

it contain NS and SOA and A records.

A stub zone is a copy of zone that contains only those resorce records nessory to identify the authoritive DNS server for that Zone.

It resolve names between two diff name space.

used to one corporate wants to use other namespace server and clients info(resolve names)

DNS Records

A - name to Ip
PTR - Ip to name
CNAME - name to name
MX - mail
NS (name server) Specifies a name server for the domain, which allows DNS lookups within various zones. Each primary and secondary name server should be declared through this record.

SOA (start of authority) Declares the host that's the most authoritative for the zone and, as such, is the best source of DNS information for the zone. Each zone file must have an SOA record (which is created automatically when you add a zone).

Client can not connect to WSUS server

Click Start, Choose Run.
In the Run box, type services.msc.
Click OK.
Right-click the Automatic Updates service.
Click Stop.
Stopping the service will take a moment.

DNS Records

1) A-Record : A records directly resolve a host to an IP address.

2) CNAME: stand for Canonical Name, or alias, where the hostname listed resolves to another hostname

3) MX: provide Mail Exchanger (E-mail) resolution for which server to use for a specific domain

4) NS : A NS record tells name servers which machines are in charge of a given domain zone.

5) PTR: that provides reverse DNS resolution or IP address to Fully Qualified Domain Name.

7) SOA: Start of Authority (or SOA) is declared. This states what DNS server has the master copy of the domain and the e-mail address of the person to contact if there are any problems

8) SPF: Send Policy Framework

9) TXT:This is also important to authenticate a mail server for a specific domain

Diffrence between GPT and GPO

GPO - Group Policy Object - Refers to the policy that is configured at the Active Directory level and is inherited by the domain member computers. You can configure a GPO – Group Policy Object - at the site level, domain level or OU level.


GPT - Group Policy Templates: The GPT is used for file-based data and stores software policy script, and deployment information. The GPT is located on the system volume folder of the domain controller. A GPO can be associated with one or more Active Directory containers such as a site, domain, or organizational.

Diffrence Between Domain Admins and Enterprise Admins

Enterprise admins are designated for the entire forest and domain admins are for specific domain only.

Enterprise Admins are the only group which can perform changes which relate directly to the forest and not an individual domain; there are very few of these tasks. For instance, Forest Prep for R2 or Exchange would need to be done by an Enterprise Admin. Creation of trust relationships between forests. Modifying the values of some object attributes/properties in AD. Creation of Terminal Services Licensing for the whole forest. Destruction of a child Domain or an entire forest. As a rule, if the Change you are planning to make would affect more than an individual domain, you will need Enterprise Admin access - and sometimes you may need Schema Admin access in addition to that.

System Admin Interview Questions

1. What is active directory schema

 

All databases have a schema which is a formal definition (set of rules) which govern the database structure and types of objects and attributes which can be contained in the database. The schema contains a list of all classes and attributes in the forest.
The schema keeps track of:

• Classes
• Class attributes
• Class relationships such as subclasses (Child classes that inherit attributes from the super class) and super classes (Parent classes).
• Object relationships such as what objects are contained by other objects or what objects contain other objects.

Active Directory schema contains formal definitions of every object class that can be created in an Active Directory forest. The schema also contains formal definitions of every attribute that can exist in an Active Directory object. This section provides the reference for each schema object and provides a brief explanation of the attributes, classes, and other objects that comprise the Active Directory schema.

 

2.  

 

 

 

what happens if domain controller is not available

if DC is not available

• users profiles or any security polices not loaded.
•  FSMO Roles are activated only in DC so when DC not available then you cannot acreate or modify objects  like users info etc.
• Roming profile or mandatory profile users cannot login.