DDR SDRAM Explained

DRAM is asynchronous, meaning it operates independently of the CPU and the system bus’ clock cycle. SDRAM is synchronous, meaning its operation is dependent on the data bus’ clock cycle (as is the CPU). This synchronicity translates to faster data transfers between memory and the CPU.

SDR (Single Data Rate) SDRAM accepts one command per clock cycle. DDR (Double Data Rate) SDRAM accepts two commands per clock cycle - on both the rising and the falling edges of each clock cycle. DDR2 achieves speeds twice as fast as DDR by using an internal clock that runs at half the speed of the data bus. DDR3 achieves speeds twice as fast as DDR2 by using an internal clock that runs at half the speed of DDR2. And… you guessed it, DDR4 is twice as fast as DDR3, due to a clock that runs at half the speed of DDR3.

DDR/DDR2/DDR3/DDR4 are not compatible, so it’s important to select the appropriate memory for your motherboard. It’s also important to match the memory chip’s speed with the motherboard specs. If your motherboard supports the DDR3-1333 standard, for example, you’ll need to purchase DDR3. As for the speed, you want to purchase memory designated DDR3-1333. However, you can get away with slower memory, just know that performance will suffer. You may be able to use faster memory if you overclock your system.


Introduction to Group Policy Objects (GPO)

How to modify the Default Domain Policy GPO

Part 1: What is Group Policy?

Part 2: Open the GPMC and find the Default Domain Policy

  • In the GPMC (Group Policy Management Console), right-click the Default Domain Policy and click Edit…
    • How to open the GPMC (Server 2003/2008_R1)
    • Expand Forest: contoso.comDomainscontoso.com (you should now see Default Domain Policy below contoso.com)

Part 3: Disable the Password must meet complexity requirements policy

  • Expand Computer ConfigurationPolicesWindows SettingsSecurity Settings (Account Policies will appear below Security Settings)
  • Select Account Policies (Password Policy will appear in the right window)
  • Double-click Password Policy (various policies will appear in the right window)
  • Double-click Password must meet complexity requirements (the Properties dialog box appears)
  • Click the Explain tab and read the explanation of this policy
  • Click the Security Policy Setting tab, click Disabled and click OK

to be continued…

IPv6 Neighbor Discovery Process (IPv6 Neighbor Discovery, SLAAC, Default Gateway assignment)

IPv6 Neighbor Discovery Process

  • Determines the link-local address of a neighbor-devices (all devices on the same  link/LAN)
  • Verifies the reachability of a neighbor
  • Keeps track of neighboring devices


IPv6 Neighbor Solicitation Message

  • Sent on the local link when a node wants to determine the link-layer address of another node on the same local link (see the figure below). When a node wants to determine the link-layer address of another node, the source address in a neighbor solicitation message is the IPv6 address of the node sending the neighbor solicitation message. The destination address in the neighbor solicitation message is the solicited-node multicast address that corresponds to the IPv6 address of the destination node. The neighbor solicitation message also includes the link-layer address of the source node.


Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6_basic/configuration/xe-3s/ip6b-xe-3s-book/ip6-neighb-disc-xe.html



IPv6 Link-layer addresses appear to be the same as Link-local addresses (are they TECHNICALLY the same?)


Surveillance Self Defense

Surveillance Self-Defense (SSD), a project of the Electronic Frontier Foundation (EFF), exists to answer two main questions: What can the government legally do to spy on your computer data and communications? And what can you legally do to protect yourself against such spying?

The Surveillance Self-Defense site aims to educate the American public about the law and technology of government surveillance in the United States, providing the information and tools necessary to evaluate the threat of surveillance and take appropriate steps to defend against it.

Technical Instructor