System Admin and IT Infra Services

A directory service...

...centralizes your organizations users and computers in one location so that you can add, update, and remove users and computers. Some popular directory services that you can set up are Windows Active Directory, OpenLDAP, and we'll dive a little deeper into both of these later on in this course.

Database servers consist of...

...database software that's running that you're able to read and write from.

LDAP notation is used for...

...entries in directory services to describe attributes using values.

When you use a static IP address, you have to keep track of...

...every IP address you assign a computer and manually entered in the network settings.

It is good practice to perform...

...infrequent full backups, while also doing more frequent differential backups

The best way to be prepared for a data loss event...

...is to have a well thought out disaster plan and procedure in place

A client discovers the address of a domain controller by...

...making a DNS query, and asking for the SRV record for the domain. The SRV record contains address information for domain controllers for that domain.

NaaS allows companies to...

...offshore their networking services so that they don't have to deal with the expensive networking hardware. Companies also won't have to set up their own network security, manage their own routing, set up a WAN and private internets, and so on.

What is one reason why we might want our own DNS server?

...so we can map our internal computers to IP addresses. That way, we can reference a computer by name, instead of IP address.

Role-Based Access Control (RBAC)

A "real-world" access control model in which access is based on a user's job function within the organization.

Redundant Array of Independent Disks (RAID)

A DATA STORAGE method of taking multiple physical disks and combining them into one large virtual disk. It is not a replacement for backups.

Centralized management

A central service that provides instructions to all the different parts of my IT infrastructure

Disaster Recovery Plan

A collection of documented procedures and plans on how to react and handle an emergency or disaster scenario, from the operational perspective

rsync (CLI)

A file transfer utility that's designed to efficiently transfer and synchronize files between locations or computers

Distribution group

A group used only for non-security functions, such as distributing email. You might this to put together an email list that included people from outside your domian.

Security group

A group used to assign rights and permissions and gain access to network resources. Contain user accounts, computer accounts, or other security groups. Default groups, like domain users and domain admins, are security groups-- they are used to grant or deny access to IT resources.

Windows Registry

A heirarchical database of settings that Windows, and many Windows applications, use for storing configuration data

Kerberos

A network authentication protocol that is used to authenticate user identity, secure the transfer of user credentials, and more

FAT32

A popular file storage system (FAT) that's compatible with Windows, Linux, and Mac OSes. But it has severe limitations on the amount of data you can store on a volume.

SMB is...

A protocol that Samba implements. When you create a Windows shared folder it's actually using the SMB protocol

Network file system, or NFS

A protocol that enables files to be shared over a network. The FAT system is compatible on all major operating systems. The easiest way to setup an NFS server is by using a Linux environment. You can install NFS server software that modify the configuration files for the directories that you want to allow shared access to. Once you do that, the NFS service will be running in the background of the server. On each client machine that wants to access a server, you just mount the file system the way you would any other file system. Except, you'd use the host name instead of a physical disk device. From there, you can access the shared directory like you would any other folder in a computer.

SMTP (simple mail transfer protocol)

A protocol used for sending emails. While POP3 and IMAP and other protocols can be used to retrieve email, there's only really one email protocol for sending email, SMTP.

FTP (File Transfer Protocol)

A protocol used to move files and folders over a network or the Internet. It's a legacy way to transfer files from one computer to another over the Internet, and it's still in use today. It's not a super secure way to transfer data because it doesn't handle data encryption. The FTP service works much like RSH service. Clients that want to access an FTP server have to install an FTP client. On the FTP server, we install the software that allows us to share information located in the directory on that server. FTP is primarily used today to share web content. If you use a website host provider, you might see that they have an FTP connection already available for use so they can easily copy files to and from your web site.

Proxy Server

A server that acts as an intermediary between a company's network and the Internet.

Group Policy Object (GPO)

A set of policies and preferences that can be applied to a group of objects in the directory. CAn contain computer configuration, user configuration, or both.

Organizational Unit

A special type of container that can hold other containers and ordinary objects.

Differential Backup

A type of partial backup that involves copying all changes made since the last full backup. Thus, each new differential backup file contains the cumulative effects of all activity since the last full backup.

nslookup

A utility that is used to test and troubleshoot domain name servers. Gives us the name server of a host or domain name.fpaas

Test environment

A virtual machine running the same configuration as the production environment, but isn't actually serving any users of the service

post-mortem

A way to document any problems you discovered along the way and most importantly, the ways you fixed them so that they don't happen again

What do you do after applying a fix in a test environment?

After applying your fix, retrace the same steps that took you to the bad experience. If your fix worked, the expected experience should now take place.

IMAP (internet message access protocol)

Allows you to download emails from your email server onto multiple devices. It keeps your messages on the email server. This email protocol is one of the more popular ways to retrieve email.

Risk assessment

Allows you to prioritize certain aspects of the organizations that are more at risk if there's an unforeseen event

Post Office Protocol, POP3

An email protocol that downloads email from an email server onto your local device. It then deletes the email from the email server. If you want to retrieve your email through POP3, you can only view it from one device.

Preventive Measures

Any procedures or systems in place that will proactively minimize the impact of a disaster

Public Cloud

Cloud services provided by a third party

HTTP status codes

Codes or numbers that indicate some sort of error or info messages that occurred when trying to access a web resource. Knowing common HTTP status code comes in handy when you're troubleshooting website error.

CUPS

Common Unix Printing System Allows you to manage printers from a simple web url.

RSoP Report

Contains everything that we need to understand what policies apply to a computer or user. It includes a whole lot of detail about where the computer and user are located in AD, what their security group memberships are and more. You can see the combined effect of all of the applied GPOs. The winning GPO column tells you which GPO ultimately took precedence for each policy and preference.

Directory Server

Contains a lookup service that provides mapping between network resources and their network addresses

Forest

Contains one or more domains. Accounts can share resources between domains in the same forest.

Reproduction case

Creating a roadmap to retrace the steps that led the user to an unexpected outcome

In the DHCP configuration settings, we can specify...

DNS server locations. The two servers then sync up and when DHCP leases out new addresses, DNS updates IP address mappings automatically.

Disaster recovery testing

Document the restoration procedures and make sure you regularly test the documentation to make sure it works now and in the future

DNS

Domain Name System. Maps human-understandable names to IP Addresses

DC

Domain component

IT infrastructure

Encompasses the software, the hardware, network, and services required for an organization to operate in an enterprise IT environment. Without an IT infrastructure, employees wouldn't be able to do their jobs and the whole company will crumble before it even get started.

XMPP

Extensible Messaging and Presence Protocol, open source protocol used in instant messaging application and social networking services. Incl. Pidgin and Padium.

Data Center

Facility that stores hundreds, if not thousands, of servers

Region

Geographical location with a number of datacenters.

NaaS

NaaS allows companies to offshore their networking services so that they don't have to deal with the expensive networking hardware. Companies also won't have to set up their own network security, manage their own routing, set up a WAN and private internets, and so on.

Batch update

Once a month and update everything (including security patches)

OUs

Organizational Units/containers of data that can contain more organizational objects/units/folders.

Functional Levels

Over the years there have been several versions of Active Directory, and we call these versions 'functional levels.' Active Directory has a functional level that describes the features it supports.

If you want an all-in-one solution to building and deploying a web application, you can use something called...

Platform as a Service, or PaaS. This includes an entire platform that allows you to build code, store information in a database, and serve your application from a single platform.

When a computer is processing the Group Policy Objects that apply to it, all of these policies will be applied in...

Precedence rules

In an infrastructure context, we call the parts of the infrastructure where certain services are executed and serve to its users...

Production

Daemons and Services

Programs that run as background processes. This means, that the program doesn't need to interact with the user through the graphical interface or the command line interface, to provide the necessary service. The operating system ensures that the program is running. Each service has one or more configuration files, that you as a system administrator will use to determine how you want the service to behave.

Local storage (pros and cons)

Pros: Data is physically nearby, low bandwidth needs Cons: Data loss due to damage at location (such as a fire, etc.)

Off site storage (pros and cons)

Pros: Data is safer in multiple locations Cons: Needs security and encryption, needs large amounts of bandwidth

Server operating systems

Regular operating systems that are optimized for server functionality

Server operating system

Regular operating systems that are optimized for server functionality. Allows more network connections, etc.

Rollback

Reverting to the previous state

SFTP

Secure File Transfer Protocol. SFTP, it's a secure version of FTP, so it makes sense to choose this option over FTP. During this SFTP process, data is sent through SSH and is encrypted. TFTP stands for trivial FTP. It's a simpler way to transfer files than using FTP.

Policies

Settings that are reapplied every few minutes and aren't meant to be changed even by the local administrators

Group Policy Preferences

Settings that, in many cases, are meant to be a template for settings

Restoration procedures

Should be documented and accessible so that anyone with the right access can restore operations when needed

Start-Transcript (Powershell)

Similar to script

Why would we want our own DNS servers?

So we can map our internal computers to IP addresses and then reference that computer by name, instead of IP address.

Server

Software or a machine that provides services to other software or machines

SSD

Solid State Drive

Replication

Stored directory data can be copies and distributed across a number of physically distributed servers, but still appear as one, unified datastore for querying and administrating

Web server

Stores and serves content to clients through the internet

ldapadd

Takes the input of an LDIF file and adds the context of the files

Lightweight Directory Access Protocol (LDAP)

Used to access information in directory services over a network.

Global (group scope)

Used to assign permissions based on roles or hierarchy within the company

Universal (group scope)

Used to group global roles in a forest. Domain local and global groups aren't replicated outside of the domain that they're defined in, but universal groups are. In a multi-domain forest, you might have a global research share readers group in each domain, and all research shared readers universal group that contains each global group has members. Universal groups are replicated to all domains in a forest.

Directory services

Useful for organizing data and making it searchable for an organization. Provide centralized authentication, authorization, and accounting (AKA the AAA)

script (linux command)

We can use it to record a group of commands as they're being issued along their output.

hat happens when there are two or more contradictory Group Policy Objects that apply to the same compute?

When computers processing the Group Policy Objects that apply to it, all of these policies will be applied in a specific order based on a set of precedents rules. GPOs are applied based on the containers that contain the computer and user account. GPOs that are linked to the least specific or largest container are applied first. GPOs that are linked to the most specific or smallest container are applied last. First, any GPOs linked at the AD site are applied then any link at the domain. And then any OUs in order from parent to child. If more than one policy tries to set the same policy or preferences, then the most specific policy wins.

Anonymous Binding

When using anonymous binding, you aren't actually authenticating at all, depending on how it's configured anyone could potentially access that directory, just like our public phone book example.

Hardware lifecycle

When was it built? When was it first used? Did the organization buy it brand new or was it used? Who maintained it before? How many users have used it in the current organization? What happens to this machine if someone needs a new one?

Resultant Set of Policy (RSoP)

When you add all of the group policies together for a specific machine and apply precedence rules to them

Simple Authentication Binding

You only need the directory name and password, which is usually in plain text and not secure at all

Infrastructure as a Service (IaaS)

You're hosting your own services in the cloud and need to decide how you want the infrastructure to look, depending on what you want to run on it

If you enable DHCP...

Your computers will be leased an IP address from a DHCP server. They'll automatically get IP addresses, and you don't have to worry about manually setting addresses. If you ever decide you need to expand your IP address range, you don't have to change anything on the client machines either, it just happens automatically.

Dnsmasq

a program that provides DNS, DHCP, TFTP and PXE services in a simple package. This will let us do some hands on configuration of these services even if it's not as complex as other networking solutions.

HTTPS, or Hypertext Transfer Protocol Secure

a secure version of HTTP. It makes sure the communication your web browser has with the website is secured through encryption. HTTPS is also referred to as HTTP over TLS or HTTP over SSL.

Advanced Group Policy Management (AGPM)

a set of add-on tools from Microsoft that give you some added provision control abilities in GPMC. If you do use AGPM in your organization, you should follow best practices for GPO version control using AGPM.

FSMO (Flexible Single Master Operations)

aka Operations Master Roles. Certain functions that can be handled by only one domain controller at a time

lftp

an ftp client program that allows us to connect to an ftp server

When we want to go to Google.com our browser is sending...

... an HTTP request to the HTTP server on the web server. In turn we get an HTTP response.

If you're running a Web server, you'll need to configure the...

... different sites and Web applications that you'd like to have enabled.

HTTP status codes that start with 5xx indicate...

... indicate an issue on the server-side. The web server that hosts this web content is experiencing issues and hopefully their server administrators are looking into it

In order to target specific groups of users or computers...

... new OUs need to be created, and users or accounts need to be added to them.

if you're running a DNS server, you'll need to configure...

... the DNS zones that you want to serve.

Directory services can also be deployed in the Cloud using...

...Directory as a Service, or DaaS providers

When managing IT infrastructure, and you want to connect a computer on a network, you have two options...

...You can grant it a static IP address or give it a DHCP assigned IP address.

You can access web servers by using...

...a domain name, such as google.com

A DHCP server is usually set up on...

...a machine or a device that has a static IP address configured to the network interface which is being used to serve the DHCP queries. That interface is then connected to the physical network that you want to configure through DHCP, which can have any number of machines on it.

When you link a GPO...

...all of the computers or users under that domain, site, or OU will have that policy applied.

Databases...

...allow us to store query, filter, and manage large amounts of data.

HTTP status codes that start with 4xx indicate...

...an issue on the client-side.

When you use Active Directory to manage a fleet of Windows servers and client machines, in addition to centralized authentication, it also...

...becomes the central repository of group policy objects, or GPOs, which are ways to manage the configuration of Windows machines.

Two of the most popular directory services that use LDAP are...

openLDAP and active directory

OU

organizational unit, such as a group

If your fleet consists mostly Windows machines you might want to look at using...

...something like Samba. Samba services are similar to NFS since she can centrally share and manage files services. Also, all major operating systems can use a Samba file sharing. The only reason you might want to consider Samba over NFS, is because it works better with Windows operating systems.

Services are usually configured to...

...start when the machine boots. So that if there is a power outage or a similar event that causes the machine to reboot, you won't need a system administrator to manually restart the service. If you want to decide yourself when the service starts, instead of starting upon boot, you need to change the software configuration to make it start when you want.

HTTP status codes that start with 2xx indicate...

...tells us the request was/is successful

When GPOs are enforced...

...they're applied according to site first and domain second. Then, any OUs are applied from least specific to most specific.

When an unexpected event occurs, your main objective is...

...to resume normal operations as soon as possible, while minimizing the disruption to business functions.

A relatively affordable solution for FAT storage hardware is to...

...use a network attached storage or NAS, pronounced NAS. Instead of setting up a dedicated server like you would other services. NASes are computers that are optimized for file storage. They usually come with an operating system best stripped down in order just to serve files over a network. They also come with lots of storage space. Whatever method you choose, central file storage and management is an important part of I.T. infrastructure for any organization.

If you want to integrate with DNS, you need the addresses of...

...your local DNS servers, what gateway you should assign, and the subnet mask that gets used. Once you solve the DHCP sever software, you have to configure the settings with this information.

On linux, configuration files for installed services are located in the ___ directory

/etc

What are the drawbacks for incremental backups?

1. Because this approach only sorts differences in the files that have changed since the last incremental backup, it's possible that all incremental backups are needed to fully reconstruct the files. 2. If one of these incremental backups is missing or corrupt it might not be possible to recover data any more recently than the last full back up. 3. Recovery might be more time consuming. This is because the most recent version of backed up data has to be recreated by integrating the last full backup with each incremental backup that follows. For super large files that are changing frequently this could require a lot of time to process.

Writing a post mortem...

1. Brief summary (what the incident was, how long it lasted, what the impact was, how it was fixed... clearly state timezone) 2. Detailed Timeline (Who was involved, what happened when, who was involved to resolve the outage/dates.times/timezone) 3. Root cause (what led to the issue, the intent is to be honest about what can be learned) 4. Resolution and recovery efforts (incl. dates, times, timezones, and should go into detail about what steps were to recover, rationale, etc.) 5. Actions to avoid the same scenario (improvements to monitoring systems, etc). Also highlight things that went well or minimized the severity of the outage.

How does DNS get set up for a website?

1. Get domain name (google.com) 2. Point new domain name to where our web content is located. Either in the DNS settings provide the IP address, or set up an authoritative DNS server for your website

Designing a disaster recovery plan means performing...

1. Risk assessment 2. Determine backup and recovery systems 3. Determine Detection and Alert Measures & test systems 4. Determine recovery methods

Two ways to set up email for a company:

1. Set up your own managed server. Using this option, you set up the email service software on a server, then you create a DNS record for your mail server. Note that there are different DNS records, and for email servers we use MX, for the mail exchange record.

What two protocols that enable us to make our web servers secure?

1. TLS 2. SSL

When looking for a reproduction case, what are the three questions you'll need to answer?

1. What steps did you take to get to this point? 2. What's the unexpected or bad result? 3. And what's the expected result?

(LDAP) Bind Operation

Authenticates clients to the directory server. Let's say you want to log in to a website that uses a directory service. You enter your account login information and password, your information is then sent back to the website. It will use LDAP to check if that user account is a user at the directory and that the password is valid. If it's valid, then you will be granted access into that account.

DCs (Domain Controllers)

Get to decide when computers and users can log into the domain 1. They host a replica of the Active Directory database and group policy objects. 2. Serve as DNS servers to provide name resolution and service discovery to clients. 3. Provide central authentication through Kerberos network security protocol 4. Whether or not users have access to shared resources/filesystems

Windows update service, list all the services registered in the system

Get-Service wuauserv (powershell)

Group scope

Has to do with the way that group definitions are replicated across domains.

Domain Computers Group

Holds all computers joined to a domain for an organization, except for the Domain Controllers, which belong in the DC group.

IaaS

IaaS providers give you pre-configured virtual machines that you can use just as if you had a physical server. Some popular IaaS providers are, Amazon Web Services and their Elastic Compute Cloud or EC2 instances, Linode, which runs out virtual servers, Windows Azure, and Google Compute Engine, which you've been using throughout this course.

Zones

If a datacenter fails in a certain geographical reason, there are others available and services can be migrated without visibly affecting users

Platform as a Service, or PaaS

If you want an all-in-one solution to building and deploying a web application. This includes an entire platform that allows you to build code, store information in a database, and serve your application from a single platform. Popular options for PaaS are, Heroku, Windows Azure, and Google App Engine.

Retirement

In this final stance, hardware becomes unusable or no longer needed and it needs to be properly removed from the fleet

Production authentication servers

Inside your company, the servers that validate users' passwords are...

IRC

Internet Relay Chat. A form of real-time Internet text messaging often used with chat sessions. Some botnets have used IRC channels to control zombie computers through a command and control server. IRC operates in a client and server model, so lots of IRC client software can be used to connect to an IRC server.

Disaster plans

Involve making regular backups of any and all critical data that's necessary for your ongoing business processes

Autoscaling

It allows the service to increase or reduce capacity as needed, while the service owner only pays for the cost of the machines that are in use at any given time. Since some machines will shut down when the demand is lower, then local disks will also disappear and should be considered ephemeral or short-lived.

TFTP (trivial FTP)

It's a simpler way to transfer files than using FTP. TFTP doesn't require user authentication like FTP, so any files that you store here should be generic and not need to be secure. A popular use of TFTP is to host installation files. A common use case for organization that want to install software over a network is to keep operating system installation files in a TFTP server. That way, when you perform a network boot, you can be automatically launched into the installer.

Secure Socket Layer protocol, or SSL

It's a way of securing communication between a web server and client. But it's pretty old and insecure, so it's been deprecated in favor of TLS. You may still see it today being used over the TLS protocol like SSL/TLS.

NTP (Network Time Protocol)

It's used to keep the clock synchronized on machines connected to a network. You've probably seen NTP implemented in your personal life if you've ever been in an airport. Airports utilize synchronized clocks systems, and many of their systems use NTP. This is because the information that you see on your departure and arrival screen has to match the time that the air traffic control team sees for their airplanes.

KVM Switch

Keyboard, video, and mouse switch. This device looks like a hub that you can connect multiple computers to and control them using one keyboard, mouse and monitor.

LDIF

Lightweight Directory Access Protocol Interchange Format

Clients

Machines that use the service requested by the server

Detection Measures

Meant to alert you and your team that a disaster has occurred that can impact operations

Active Directory (AD

Microsoft's centralized directory database that contains user account information and security for the entire group of computers on a network.

Hybrid cloud

Mixture of both public and private clouds

Cloud computing

The concept that you can access your data, use applications, store files, et cetera, from anywhere in the world as long as you have an internet connection. But the Cloud isn't a magical thing. It's just a network of servers that store and process our data.

Apache

The most commonly used HTTP server, open source

Group Policy Management Console (GPMC)

The most important tool we'll use for creating and viewing a group policy object.

Transport Layer Security protocol, or TLS

The most popular way to keep communications secure over a network. TLS is widely used to keep web browsing secure, but it can be used in a lot of other applications, too.

Workgroup Computer

The name comes from Windows workgroups which are a collection of standalone computers that work together. Windows workgroups aren't centrally administered so they become harder and harder to manage as the size of the network grows.

Data recovery

The process of trying to restore data after an unexpected event that results in data loss or corruption

procurement

The stage where hardware is purchased or re-used for any employee

SASL (Simple Authentication and Security Layer)

This employs the help of security protocols such as TLS (in Kerberos). Requires the client and the directory server to authenticate using the same method.

Domain local (group scope)

This is used to assign permission to a resources, for example, a domain local group that has 'read' access to a network share code.

Secondary or Stand-By Machine

This machine will be exactly the same as a production machine, but won't receive any traffic from actual users until you enable it to do so

Group Policy Settings Reference

This reference is a spreadsheet that details the GPO policies and preferences that are available and where to find them.

Start-Transcript -Path C:\Transcript.txt

This will write the contents of the session to C:\Transcript.txt. When you want to stop recording you need to call Stop-Transcript. The file created is a plain text file where the commands executed and their outputs are stored.

script session.log

This will write the contents of your session to the session.log file. When you want to stop recording, you can write exit or press Ctrl-D. The generated file will be in ANSI format which includes the colors that were displayed on screen. In order to read them, you can use commands like ansi2txt or ansi2html to convert it to plain text or HTML respectively.

Corrective/recovery measures

Those enacted after a disaster has occurred

Canaries

When you use a small group of servers to detect any potential issues in the larger changes you want to push out in the system. Once you verify that it works correctly on those machines, you then deploy the change to the rest of the fleet. That way, if there's an issue with the change, only a subset of the users get exposed to it, and you can roll it back before it hits everyone.

Private cloud

When your company owns the services and the rest of your infrastructure--whether on-site or in a remote data center

Deployment

Where hardware is set up so that the employee can do their job

Maintenance

Where software is updated and hardware issues are fixed if and when they occur

Regular incremental backup vs. differential backup

While a differential backup backs up files that have been changed or created since the last full backup, an incremental backup is when only the data that's changed in files since the last incremental backup is backed up

Setting up an NTP server

You can't depend on the hardware itself to keep consistent time, so you might want to set up an NTP server. There are different ways that an IT support specialist or sysadmin can do this for an organization. You can use a local NTP server or a public NTP server. To set up a local NTP server, you can install NTP server software on your management server. Then, you install NTP clients on your machines and tell those computers which NTP service to sync their time to. This is a great option because you can then manage the entire process from end to end. The other way to set up NTP is to use a public NTP server. Public NTP servers are managed by other organizations that your client machines connect to in order to get synchronized time. This is an awesome way to utilize NTP without having to run a dedicated NTP server. But if you have a large fleet of thousands of machines, it's better etiquette to be running your own NTP servers. Another good practice is to run your own NTP server. Then, have that point to a public NTP server. This makes it so that you don't connect all your clients to a public NTP server, and you don't have to measure time synchronization.

If you're managing an organization's website on a server, how do you enable TLS on the server so that the site can be using HTTPS?

You need to get a digital certificate of trust from an entity called a certificate authority. The certificate authority grants a certificate to your website saying that it trusts that you control the web server and verifies that you are who you say you are. Once it does that, you can install the certificate on your web server. That way, when users visit your site, they'll see the HTTPS in the URL instead of just HTTP.

service ntp service

checks if there is an ntp service running on Linux

CN

common name

dn

distinguished name

Load balancer

ensures that each VM receives a balanced number of queries. Whenever there's a request for your website, a different VM will be picked to serve the response.

Full backup

involves making a copy of the data to be fully backed up. The full unmodified contents of all files to be backed up is included in this backup mechanism whether the data was modified or not. In the case of data that doesn't change very often, like operating system configuration files, this approach can be inefficient. You're backing up multiple copies of data that isn't changing, which waste space and uses bandwidth unnecessarily.

ldapmodify

modifies an existing object

IaaS providers give you...

pre-configured virtual machines that you can use just as if you had a physical server.

check that there is an ntp daemon running

service nap status (linux)

Provisioning

setting up service - physical installation, software configuration;

To configure a DHCP server, you need to figure out...

which IP range you can use to assign IP addresses.

ldapdelete

will remove the object that the LDIF file refers to

ldapsearch

will search for entries in your directory database