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Computing Terms

ASCII (American Standard Code for Information Interchange)is a 7 bit code representing 128 common characters used in day to day communications.Since everything you do on the computer is based on data, and data can be represented in hex, and hex can be represented in binary, and binary is just a ‘1’ or a ‘0’, it makes sense that the alphabet and other common characters are represented by numbers. The ASCII table is the standard representation of this conversion – see link for more detail. (

Binary ( The binary or base-two numeral system is a system for representing numbers in which a radix of two is used; that is, each digit in a binary numeral may have either of two different values. Typically, the symbols 0 and 1 are used to represent binary numbers. Owing to its relatively straightforward implementation in electronic circuitry, the binary system is used internally by virtually all modern computers.

Bit In computer terms, a bit is smallest data element that can be stored. It can have only two states which directly represent the media it is stored on; on hard and floppy disk media, the data element is a magnetic charge or lack there of; In your computer circuits and computer chips, it consists of an electric charge or lack there of; on optical media, it consists of reflecting light or the lack of reflection. This leads to your common technician’s referral to ones and zeros – all data can be broken down to the base element of a one or a zero… which leads you to the binary numeral system of math.

In computer terms, a byte is a combination of 8 bits in sequence. The 8 bits (consisting of 1s and 0s) can be translated into a binary number. Since binary and hex share a common base of 2, binary numbers are typically translated to hex for easier notation; beyond that, many times hex numbers are converted to base 10 decimal so that the normal graduate can understand them as well. The most common binary and hex terms seen by people are Internet Protocol (IP) addresses. Your home machine is assigned an address which makes it unique* to all other computers in the world – if you were to go to the Command prompt and type “ipconfig”, you would see an IP Address similar to** and a Subnet Mask similar to – these numbers are represented by the hex numbers C0.A8.01.05 and FF.FF.FF.00 and the binary numbers 11000000.10101000.00000001.00001001 and 11111111.11111111.11111111.00000000.
Default Gateway A default gateway is used when you want to communicate to other hosts that do not reside on your local network. The default gateway is the destination that your PC sends network packets to when the subnet mask indicates that the destination host is not local. The default gateway is like your local USPS post office, which takes mail destined for remote places. For any delivery locally (on your own network), you can yell and the host (your neighbor) can hear you – in networking terms, this is called your broadcast domain or the local network that your PC is connected to.

Dynamic Host Configuration Protocol is an application which automatically provides IP Addresses* to PCs on a network from a pre-configured pool that has been designated for use. In larger networks hosts are used to run the DHCP application whereas in small business or home networks, the DSL or Broadband router/modem has the functionality built in. On the client PC, the DHCP Client functionality must be enabled on network interfaces that you wish to automatically configure upon boot.
* IP Addresses includes the addresses for the local PC, the subnet mask, the default gateway and DNS servers.

A Demilitarized Zone, or DMZ, is an area behind the firewall that is protected from the enemy (hackers) but still allows legitimate external users to access. A DMZ is most frequently used as a home for any hosts that you have that your clients need access to, such as your corporate web server.

Domain Name Services is a tool to look up or resolve host IP Addresses on the Internet or local network. Forward DNS is the typical resolution type, where you provide your PC browser or application a URL or FQDN and the DNS client built into your PC operating system queries DNS servers to get an IP Address to send the request or get the information from. This lookup is the equivalent to finding a phone number by looking up a name in your local phone book.

A firewall is used to protect your personal or private network and hosts on the network. Typically, a firewall is a network hardware device that has 2 or more network interfaces which are specifically configured to allow or reject network traffic of your choice to and from your network or PC to the Internet. Software firewalls are becoming more prevalent for home use or roaming users who VPN into their local networks. ZoneAlarm and Microsoft XP’s built in firewall are two great products that are easily configured and provide pop-up style notification when access to your PC is attempted from the Internet.

Fully qualified domain names are the same as URLs but do not include the path portion of the URL. For example, is the FQDN to LOGIC Integrity’s Internet web site.

Hexadecimal (
In mathematics and computer science, hexadecimal or simply hex is a numeral system with a radix or base of 16 usually written using the symbols 0–9 and A–F or a–f. The hexadecimal system was first introduced to the computing world in 1963 by IBM.

A host in network terms is any device on an IP based network that is assigned an IP Address.Typically, even though network devices are hosts in the true sense of the word, the term hosts is used to refer to file servers and PCs.

A hub is a data packet repeater that is not intelligent. It will forward data packets to all connected hosts and the hosts much determine if the packet has their address on it - if not, the host discards the packet. This is typically called a Layer 2 device.

IP Address
Internet Protocol address. Often referred to as a TCP/IP address incorrectly, since TCP (Transport Control Protocol) actually refers to the communication that operates on the Internet. Consider the IP address similar to your street address and the TCP protocol similar to the type of vehicle you drive. TCP is very common since it actually checks to verify delivery of data in a “session”; the alternative is UDP (User Datagram Protocol) which is “session less” and does not confirm delivery.

Internet Protocol Security, commonly known as IPSEC, is an encryption mechanism that allows secure data transmissions between clients and hosts. IPSEC, often combined with Virtual Private Network solutions in tunnel mode, is an industry standard that most communications providers support. The challenge with IPSEC solutions is that multiple TCP ports are required beyond the standard http (TCP port 80) and https (TCP port 443) which limits its usefulness in some environments where firewalls have been tightened to prevent IPSEC tunnels. SSL VPN solutions are now becoming prevalent since they use only https (TCP port 443) and are more reliable on a variety of internet service provider (ISP) networks.

MAC Address
Media Access Control address - this is a hexadecimal 12 digit number that is unique to each and every network interface attached to the Internet as a whole. The uniqueness is important since no two devices can have the same "address" since they would not be distinguishable at a hardware level.

Private Network
A private network is the portion of your network that is behind your firewall and is “safe” from Internet attack when operated properly. Typically your employee PCs are located on the private network and the IP Address assigned to each PC is translated (NAT) before it is placed on the public Internet. Typical small network routers (Linksys, D-Link, etc.) will default to the private* address space which is not valid on the Internet since Internet routers are configured to ignore this address space. For more detail, you can read RFC1918 at located at

* private address space is designated by the governing body of the Internet to allow hosts not directly connected to the Internet to not waste
limited external IP Addresses.

A router is used to move data packets (similar to USPS mail packages) between remote networks by routing data via the default gateway (similar to the local USPS office). This is typically called a Layer 3 device.

Secure Sockets Layer is an encryption mechanism to encrypt data while in transport. Whenever you conduct business over the internet, always ensure that the browser URL is "https:" and that the certificate is trusted (i.e. click on the lock in the bottom right hand of your status bar and validate that the site name and certificate match).

Subnet Mask
A subnet mask is used in conjunction with an IP Address to determine the network boundary for your IP Address. It would be similar to the ZIP Code that USPS uses in that the ZIP gets you to the right geographic area while the IP Address gets you to the right house.

A switch is a data packet repeater (gets a packet and retransmits it) that is smart enough to learn
host MAC addresses and forward packets specifically to them. It is only useful on the local network. This is typically called a Layer 2 device.

A Uniform Resource Locator record is the registered name and path to an IP based network resource. For example, is a URL to LOGIC Integrity’s data dictionary available online.

A Virtual Private Network is created when a remote workstation on the public Internet attached to your local network and for all purposes, behaves like it is local to the network. It is important that encryption protocols are implemented for VPN configurations so that any intercepted traffic is not decipherable. Authentication should also be enforced with strong passwords (more than 8 characters, minimum of 3 character sets) so that hackers can not easily or automatically determine your users’ passwords and compromise your network and data.

A Virtual Private Network that is based on SSL has a distinct advantage over standard IPSEC VPN solutions. A SSL based remote solution only requires the network and internet between the remote site and the home site to pass TCP port 443 (standard for SSL). This makes it much more compatible since internet cafe's, businesses and wireless providers never block TCP port 443 since it is required for all secure web site access. A great new SSL VPN solution on the market is the Netgear FVS336G or the Sonicwall series which offer full remote VPN capabilities at fraction of the price.