1z0-033:Oracle9i Database:Performance Tuning

ORACLE公司於1979年,首先推出基於SQL標準的關系數據庫產品,可在100多種硬件平臺上運行(所括微機、工作站、小型機、中型機和大型機),支持很多種操作系統。用戶的ORACLE應用可方便地從壹種計算機配置移至另壹種計算機配置上。ORACLE的分布式結構可將數據和應用駐留在多臺計算機上,而相互間的通信是透明的。1992年6月ORACLE公司推出的ORACLE7協同服務器數據庫,使關系數據庫技術邁上了新臺階。根據IDG(國際數據集團)1992年全球UNIX數據庫市場報告,ORACLE占市場銷售量50%。它之所以倍受用戶喜愛是因為它有以下突出的特點:支持大數據庫、多用戶的高性能的事務處理。ORACLE支持最大數據庫,其大小可到幾百千兆,可充分利用硬件設備。支持大量用戶同時在同壹數據上執行各種數據應用,並使數據爭用最小,保證數據壹致性。系統維護具有高的性能,ORACLE每天可連續24小時工作,正常的系統操作(後備或個別計算機系統故障)不會中斷數據庫的使用。可控制數據庫數據的可用性,可在數據庫級或在子數據庫級上控制。ORACLE遵守數據存取語言、操作系統、用戶接口和網絡通信協議的工業標準。所以它是壹個開放系統,保護了用戶的投資。美國標準化和技術研究所(NIST)對ORACLE7 SERVER進行檢驗,100%地與ANSI/ISO SQL89標準的二級相兼容。實施安全性控制和完整性控制。ORACLE為限制各監控數據存取提供系統可靠的安全性。ORACLE實施數據完整性,為可接受的數據指定標準。

1z0-033:Oracle9i Database:Performance Tuning,1z0-033屬於ORACLE認證考試科目之壹,9i DBA 1z0-033考試題庫由KillTest認證題庫網資深IT認證講師和9i DBA產品專家結合PROMETRIC或VUE的真實1z0-033考試環境最新原題傾心打造。1z0-033涵蓋192道真題,真題更新時間:2008年11月12日。9i DBA 1z0-033(Oracle9i Database:Performance Tuning)考題由我們的資深IT認證講師和9i DBA產品專家精心打造,包括了當前最新的真實1z0-033考題,全部附有正確答案。

Oracle壹個最主要的特點:支持分布式數據庫和分布處理。ORACLE為了充分利用計算機系統和網絡,允許將處理分為數據庫服務器和客戶應用程序,所有共享的數據管理由數據庫管理系統的計算機處理,而運行數據庫應用的工作站集中於解釋和顯示數據。通過網絡連接的計算機環境,ORACLE將存放在多臺計算機上的數據組合成壹個邏輯數據庫,可被全部網絡用戶存取。分布式系統像集中式數據庫壹樣具有透明性和數據壹致性。具有可移植性、可兼容性和可連接性。由於ORACLE軟件可在許多不同的操作系統上運行,以致ORACLE上所開發的應用可移植到任何操作系統,只需很少修改或不需修改。ORACLE軟件同工業標準相兼容,包括許多工業標準的操作系統,所開發應用系統可在任何操作系統上運行。可連接性是指ORALCE允許不同類型的計算機和操作系統通過網絡可共享信息。

640-802:Cisco Certified Network Associate(CCNA)

CCNA認證(CCNA-思科網絡安裝和支持認證助理)是整個Cisco認證體系中最初級的認證,同時它也是獲得CCNP認證、CCDP認證和CCSP認證的必要條件(CCIP認證、CCIE認證不強制要求),而且許多Cisco專業認證(Cisco Qualified Specialist)也要求考生首先得CCNA認證。CCNA認證屬於Cisco售後工程師認證體系得入門認證,通過CCNA可以證明妳已掌握網絡得基本知識, 並能初步安裝、配置和操作Cisco路由器、交換機及簡單的LAN和WAN。CCNA認證表示經過認證的人員具有為小型辦公室/庭辦公室(SOHO)市場聯網的基本技術和相關知識。通過CCNA認證的專業人員可以在小型網絡(100或100以下個節點)中安裝、配置和運行LAN、WAN和撥號訪問業務。他們可以使用的協議包括(但不限於)IP、IGRP、 IPX、Serial、Apple、Talk、Frame、Relay、IP RIP、VLAN RIP、Ethernet、Access Lists。
 
640-802科目屬於Cisco認證體系中CCNA的指定考試科目,640-802:Cisco Certified Network Associate(CCNA),640-802最新更新版涵蓋了183道真題,2008年11月12日進行了最新更新。CCNA 640-802考試題庫由KillTest認證題庫網資深IT認證講師和CCNA產品專家結合PROMETRIC或VUE的真實640-802考試環境最新原題傾心打造。CCNA 640-802(Cisco Certified Network Associate(CCNA))考題由我們的資深IT認證講師和CCNA產品專家精心打造,包括了當前最新的真實640-802考題,全部附有正確答案。所有購買KillTest 640-802 題庫的客戶都將得到60天的免費升級服務,保證了客戶的壹次通過率。KillTest IT認證題庫網助您壹次通過CCNA 640-802考試。

CCNA認證在考試條件上沒有任何的要求,只需要考生持有2個有效證件,如身份證和信用卡、駕駛證、學生證、護照等。CCNA認證的考試編號為640-802,時間為90分鐘,題目:50-60題,總分為1000分,考生需達到849分就可以過關。考試類型為:模擬題;少數連線題;多項選擇題及單項選擇題。

CCNA Security Exam Tutorial:When It’s Good To Add Salt

When you started studying for your CCNA certification exam, one of the very first things you learned was the major difference between the enable password and the enable secret – the enable secret is encrypted by default, where the enable password is just sitting there in clear text, waiting to be read!

When you look at the enable secret in a Cisco router configuration, it looks like it would be impossible to guess. 640-802:Cisco Certified Network Associate(CCNA) After setting the enable secret on this router to the word security, here’s how it appears in the configuration:enable secret 5 $1$24me$gVFxUOI4gYp0IQbhtH8Rz0.That password has been encrypted by MD5, the Message Digest 5 algorithm. The result of the MD5 algorithm being applied to the password is a 32-character hexadecimal value.

That password is hard to guess, but not terribly hard to crack. Anyone looking over your shoulder would not be able to come up with that password, but there are readily-available password cracking software devices that can crack that encryption in a matter of minutes. That’s true of any MD5-encrypted password, not just those on Cisco routers.So what can we do about this? We can add SALT to our MD5.

The salt itself is simply a string of random characters that are added to the encryption process. Salting makes it much more difficult for a hacker to come up with the password; each bit added by the salt process literally makes it twice as difficult for the password to be compromised. A recent Wikipedia entry states that if a password was one of 200,000 words, a 32-bit salt would require 800 trillion hashes for a full-blown brute force attack.

The actual creation and application of a salt is beyond the scope of the CCNA Security exam, but once you’ve earned that valuable certification – or maybe while you’re preparing for it – do a Google search on “salt md5” and read up on this powerful security tool. In the meantime, look for more CCNA Security tutorials on the site you’re on now as well as my website!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 100 free certification exam tutorials, including Cisco CCNA certification test prep articles. His exclusive Cisco CCNA study guide and Cisco CCNA training is also available! Visit his blog and sign up for Cisco Certification Central, a daily newsletter packed with CCNA, Network+, Security+, A+, and CCNP certification exam practice questions! A free 7-part course, “How To Pass The CCNA”, is also available, and you can attend an in-person or online CCNA boot camp with The Bryant Advantage!