What are CN, OU, DC in an LDAP search?

CN = Common Name

OU = Organizational Unit

DC = Domain Component

These are all parts of the X.500 Directory Specification, which defines nodes in a LDAP directory.

You can also read up on LDAP data Interchange Format (LDIF), which is an alternate format.

You read it from right to left, the right-most component is the root of the tree, and the left most component is the node (or leaf) you want to reach.

Each = pair is a search criteria.

With your example query

("CN=Dev-India,OU=Distribution Groups,DC=gp,DC=gl,DC=google,DC=com");

In effect the query is:

From the com Domain Component, find the google Domain Component, and then inside it the gl Domain Component and then inside it the gp Domain Component.

In the gp Domain Component, find the Organizational Unit called Distribution Groups and then find the object that has a common name of Dev-India.

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What are CN, OU, DC?

From RFC2253 (UTF-8 String Representation of Distinguished Names):

String X.500 AttributeType

------------------------------
CN      commonName
L       localityName
ST      stateOrProvinceName
O       organizationName
OU      organizationalUnitName
C       countryName
STREET  streetAddress
DC      domainComponent
UID     userid

The string ("CN=Dev-India,OU=Distribution Groups,DC=gp,DC=gl,DC=google,DC=com") is a path from an hierarchical structure (DIT = Directory Information Tree) and should be read from right (root) to left (leaf).

It is a DN (Distinguished Name) (a series of comma-separated key/value pairs used to identify entries uniquely in the directory hierarchy). The DN is actually the entry's fully qualified name.

Here you can see an example where I added some more possible entries. The actual path is represented using green.

https://i.stack.imgur.com/0XJKi.png

The following paths represent DNs (and their value depends on what you want to get after the query is run):

"DC=gp,DC=gl,DC=google,DC=com"

"OU=Distribution Groups,DC=gp,DC=gl,DC=google,DC=com"

"OU=People,DC=gp,DC=gl,DC=google,DC=com"

"OU=Groups,DC=gp,DC=gl,DC=google,DC=com"

"CN=QA-Romania,OU=Distribution Groups,DC=gp,DC=gl,DC=google,DC=com"

"CN=Dev-India,OU=Distribution Groups,DC=gp,DC=gl,DC=google,DC=com"

"CN=Diana Anton,OU=People,DC=gp,DC=gl,DC=google,DC=com"

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I want to add somethings different from definitions of words. Most of them will be visual.

Technically, LDAP is just a protocol that defines the method by which directory data is accessed.Necessarily, it also defines and describes how data is represented in the directory service

https://i.stack.imgur.com/cxKaO.png

To navigate the DIT we can define a path (a DN) to the place where our data is (cn=DEV-India,ou=Distrubition Groups,dc=gp,dc=gl,dc=google,dc=com will take us to a unique entry) or we can define a path (a DN) to where we think our data is (say, ou=Distrubition Groups,dc=gp,dc=gl,dc=google,dc=com) then search for the attribute=value or multiple attribute=value pairs to find our target entry (or entries).

https://i.stack.imgur.com/iF4C7.png

If you want to get more depth information, you visit here

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At least with Active Directory, I have been able to search by DistinguishedName by doing an LDAP query in this format (assuming that such a record exists with this distinguishedName):

"(distinguishedName=CN=Dev-India,OU=Distribution Groups,DC=gp,DC=gl,DC=google,DC=com)"

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