DHCP Dynamic Host Configuration Protocol (Farsi User Guide)
Resource: Windows 2000 Server Resource kit TCP/IP Core Networking Guide

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DHCP Database
 

Database مربوط به هر یک از DHCP Server درون خود نگهداری می شود و کاملا این Data بصورت Dynamic در هر لحظه می تواند UpDate شود . ومانند Wins Server این اطلاعات پخش

نمی شود در دسته های کوچکتر در هر سرور نگهداری می شود.

 
Database Management

وظیفه ایجاد ونگهداری و مدیریت Database در DHCP Serv بر عهده خود سرور می باشد .البته خود Admin نیز می تواند عملیات Edit را بر روی Database داشته باشد در موارد خاص .

 
Record Management

تعداد رکورد موجود در Database بدون محدودیت می باشد .مفدار آن بستگی مستقیم با تعداد Client های دارد که در شبکه  می باشند و سرور IP گرفته اند البته خود سرور در زمانهای خاصی  شروع به پاکسازی

رکوردهای اضافه می کند .

 
Storage Space Management

در زمانهای که سرور در شبکه بیکار می شود شروع به کاهش دادن مقدار فضای اشغالی توسط Database خود می کند . امکان دارد این کار در ماه یک بار انجام شود در سرور هایی که بیش از 1000 رکورد را در خود

نگهداری می کنند امکان دارد سیستم بدلیل بار کاری زیاد نتواند این عمل را زود به زود انجام دهد برای اینکه سرور این کار را بکند Admin می تواند این کار را بصورت دستی نیز انجام دهد .

در قسمت Troubleshooting می توانید مراحل جابجایی یک DHCP Database از یک سرور به سرور دیگر را مشاهده کنید .

Database Backup

در زمانهای خاصی سرور از Data خود یک Backup می گیرد که درآدرس Registry این سرویس در  قسمت BackupInterval می توان این زمان را مشخص کرد .

 

 
DHCP Service Database File
%SystemRoot%\System32\Dhcp directory

 در جدول زیر نام این فایلها و نیز موارد استفاده آنها را مشاهده می کنید . تذکر محل این فایلها در آدرسی که مشاهده می کنید می باشد .

File Description
J50.log and J50xxxx.log A log of all transactions done with the DHCP database. This file is used by DHCP to recover data if necessary.

To increase speed and efficiency of data storage, the Jet database writes current transactions to log files rather than to the database directly. Therefore, the most current view of the data is the database plus any transactions in the log files. These files are also used for recovery if the DHCP service is stopped in an unexpected manner. If the service is stopped in an unexpected manner, the log files are automatically used to recreate the correct state of the DHCP database.

Log files are always a certain size; however, they can grow quickly in number on a very busy DHCP server. It is inevitable that DHCP will write more transactions to a log than the size of the log can accommodate. When a log file becomes filled, it is renamed to indicate that it is an older log and not in use. A new transaction log is created with the Jn.log filename (where n is a decimal number), such as J50.log. The naming format of the previous log file will be Jetxxxxx.log, where each x denotes a hexadecimal number from 0 to F. Previous log files are maintained in the same folder as the current log files.

The log files are processed (all log entries written to the database) and deleted when a successful backup occurs or when the DHCP server is shut down gracefully. Therefore, if many Jn.log files have accumulated, frequent backups should be scheduled to maintain the logs.

After the entries have been processed, it is possible to manually delete the log files; however, this prevents a successful recovery of the database if it is needed. Because of this, it is important that the log files not be manually deleted or removed from the system until a backup has been performed.

J50.chk A checkpoint file that indicates the location of the last information successfully written from the transaction logs to the database. It is also used for recovery purposes—that is, the checkpoint file indicates where the recovery or replaying of data should begin. This checkpoint file is updated every time data is written to the database file (DHCP.mdb).
Dhcp.mdb The DHCP service database file that contains two tables: the IP-address-Owner-ID mapping table and the name–to–IP address mapping table.
Dhcptmp.mdb A temporary file that is created by a DHCP server. This file is used by the database as a swap file during index maintenance operations and may remain in the %SystemRoot%\System32\DHCP directory after a crash.
Resx.log These are reserved log files that are kept for emergency purposes. They are used if the server runs out of disk space. If a server attempts to create another transaction log file and there is insufficient disk space, the server flushes any outstanding transactions into these reserved log files. The service then shuts down and logs an event to the event log.
 
DHCP Dynamic Host Configuration Protocol (Farsi User Guide)

LastUpdate:2005/04/05

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