What The FAQ

Question: What are the common transmission rates for Ethernet?

The common transmission rates for Ethernet are:

10 Mbps – 10BASE-T Ethernet

100 Mbps - 100BASE-T Ethernet (Fast Ethernet)

1 Gbps (1000 Mbps) - 1000BASE-T Ethernet (GbE)

Question: What is the difference between half and full duplex mode in Ethernet?

As you know we can set half or full duplex mode (10Mbps full duplex, 100Mbps half duplex, 1000Mbps full duplex, etc) on network card, switch port or other networking devices, but what is the difference between these two modes?

Half duplex mode enables networking devices to send data one-way at a time, means both networking devices cannot send data at the same time. It’s like walkie-talkie, only one person can talk at a time.

Let's talk about full duplex, it enables two networking devices to send data at the same time and it improves network performance. It’s like making a call to your friend by using telephone or cell phone, both of you can talk and listen at the same time.

Question: What are the transmission speed for Cat 5, Cat 5e, Cat 6 network cable?

Cat 5 and Cat 5e UTP cables can support 10/100/1000 Mbps Ethernet. Although Cat 5 cable may support to some degree in Gigabit Ethernet (1000 Mbps), it performs below standard during high-data transfer scenarios, so I do not recommend you to use Cat 5 cable in Gigabit Ethernet, use Cat 5e instead (of course Cat 6 is the best).

Cat 6 UTP cable is manufactured targeting on Gigabit Ethernet and backward compatible with 10/100 Mbps Ethernet. It performs better then Cat 5 cable with higher transmission rate and lower transmission error. If you plan to have Gigabit network, look for Cat 5e or Cat 6 UTP cables.

Note: Cat 3 UTP cable? Forget about it... It's not popular anymore since it can only support 10 Mbps Ethernet.

Question: What is the maximum connection length for Cat 5, Cat 5e, Cat 6 network cable?

The maximum connection length for different UTP cables between networking devices:

Cat 5 – 100 meter (328 feet)

Cat 5e – 100 meter (328 feet)

Cat 6 – 100 meter (328 feet)

Of course you can run cable more than specified maximum length, but the network performance might be dropped due to packet loss and transmission error.

Question: What is the difference between router, hub and switch?

Router is mainly used to route network traffic from one network to another network. Most of the home network router is NAT router, which is used to route traffic between home network and Internet. NAT (Network Address Translation) means all home network IPs will be translated to broadband WAN IP when accessing to Internet. Also you can see that home router is usually equipped with 4-8 switch ports.

How about hub and switch? Both are networking devices that commonly deployed to expand the existing network by connecting additional computers to router. If you have choice, use switch instead of hub. Why? Switch is more intelligent than hub! When a computer sends a packet, switch will only send that packet to the destination computer, whereas hub will broadcast that packet to all computers in the network and slow down the network speed.

Question: What is TCP/IP?

TCP/IP is very popular protocol suite, which is used in Ethernet home network, wireless network and Internet. TCP/IP stands for Transmission Control Protocol/Internet Protocol, named after these 2 popular protocols (TCP, IP). Of course there are many other protocols in this protocol suite.

The TCP/IP protocol suite contains 4 layers, and each layer works with specific functions and protocols.

Layer 4 Application Layer – This is the highest layer of TCP/IP protocol suite. This is the layer that closest to the end users, which it deals with applications that we use daily and also talks to the Transport layer. Those applications could be Web browser (HTTP, HTTPS) , email program (SMTP, ESMTP, POP3, IMAP) , telnet, SSH, BitTorrent and other networking applications.

Layer 3 Transport Layer - The Transport layer is mainly in charge of how to send the data to the destination after receiving the request from Application layer. TCP and UDP are 2 main protocols in this layer which can provide connection oriented or connectionless methods to transfer the data.

Layer 2 Internet Layer - IP (IPv4, IPv6) is the main protocol in Internet layer. This layer will read the source and destination IP address of packet, and then route to destination computer. Other protocols that belong to this layer are ARP, RIP, BGP, IPsec, ICMP, IGMP and RSVP.

Layer 1 Network Access Layer - Lowest layer of TCP/IP protocol suite and is the physical layer that do the actual data transmission using raw bits (0, 1). The popular implementations are different types of Ethernet or wireless network, PPP, DSL, xDSL and ISDN.

Questions: Why do we need to configure LAN and WAN (Internet) IP settings on home router?

Normally you are required to configure LAN and WAN (Internet) IP settings on home router, but you might wonder why?

The WAN (Internet) IP is used by your home router to communicate to Internet servers via Cable/DSL modem, whereas the LAN IP is acted as gateway IP on your home network, so that other computers can set the router's LAN IP as gateway IP and access to Internet via router. Usually the LAN IP is private IP (cannot be used on Internet), such as 192.168.x.x and 10.x.x.x. Then how can the home computer with private LAN IP access to Internet? Ha.. Because there is built-in NAT (Network Address Translation) on router that will translate the computer’s LAN IP to WAN Internet IP when accessing to Internet.

Question: What is loopback IP address?

Loopback IP address is, the IP address that represents your computer itself by default if your network card works well. This IP address is commonly used as troubleshooting tool to test operation of network card or network program access on computer itself.

Question: What is the difference between IPv4 and IPv6?

IPv4 means Internet Protocol version 4, whereas IPv6 means Internet Protocol version 6.

IPv4 is 32 bits IP address that we use commonly, it can be, or other 32 bits IP addresses. IPv4 can support up to 232 addresses, however the 32 bits IPv4 addresses are finishing to be used in near future, so IPv6 is developed as a replacement.

IPv6 is 128 bits, can support up to 2128 addresses to fulfill future needs with better security and network related features. Here are some examples of IPv6 address:




Question: What is IP routing?

IP routing is the process of sending data from one computer to another computer that sits in another network through router.

The router is also the gateway that we usually set on computer. This gateway is the default router for the computer, means all network traffic that destined to other network’s computer would go through this gateway unless specified differently in the routing table.

Question: What is routing table?

Routing table is actually a table that shows you the routes that you have set on the Windows OS, network routers or other network devices. The computer or network devices will know how to do routing based on this routing table.

Here is an example of routing table in Windows OS by just opening the command prompt and then type netstat –r or route print. Quite simple to understand it, the computer will send the network packets to the Gateway that tie to particular Network Destination. Example again, the computer will send the network packets to if the destination is in multicast network.

Please note the gateway shown with network destination is default gateway. If no specific route found, all the network traffic will be sent to default gateway for routing.

Question: What is NAT (Network Address Translation)?

NAT (Network Address Translation) means the process to change the source and/or destination IP address of network IP packets when they pass through a router as according to network address translation configuration.

For typical home network setup, all home network’s source IP addresses (private IP addresses) will be translated to broadband WAN IP when accessing to Internet, and also the source port of IP packet will be translated too, so that several computers can access to Internet with one Internet connection one WAN IP address by using router that performs NAT. Thy type of NAT is also called PAT (Port Address Translation).

Question: How does proxy server work?

Proxy server works as intermediate server to send the requests (http,ssl,ftp,etc) to other servers on Internet on behalf of other computers, so that can hide the identity of actual requester. It is like a middle man, works between the user's computer and the server that user tries to download web pages or files off.

As an example, a user can send a http request from the computer to proxy server, then the proxy server will communicate with the web server (computer won’t talk to web server directly) and then return the web page information back to the user’s computer, so that the user’s computer IP can be hidden and prevent unauthorized access to user's computer through the Internet. This kind of proxy server is also called anonymous proxy server.

There are also additional features can be implemented on proxy servers, such as filter to check and warn you on phishing, spyware or other unsecured websites, URL website blocking filter and caching to improve request response time. The proxy server can be a program installed on computer, proxy server set up on your home network or the public proxy server on Internet.

Questions: What is Wake-on-LAN (WOL)?

Wake-on-Lan (WOL) is the implementation to power up your computer remotely from other computer over the Internet or within your home network by using special packet, called magic packet.

You can only do this if your computer’s motherboard supports the WOL feature, and you can usually locate and enable it under Power Management section in motherboard’s BIOS setup page. Also you need to enable the WOL feature on network card as well to reserve power.

After that, you can install some WOL programs (Fusion WOL, Depicus WOL, etc) on other computer to power up this computer remotely. If you don’t like, you can also use the following Internet based WOL applications to power up your computer.

Question: What is QoS (Quality of Service)?

QoS or Quality of Service is getting popular nowadays! You can find it on your router management page as well if it’s supported. So what is it about?

It’s actually a network mechanism to reserve the network resource (bandwidth) in order to provide better service and give higher priority to certain network traffic flows, such as online gaming, video conferencing, VoIP, Bittorrent and other bandwidth consuming applications.

In order to implement simple QoS on home or SOHO router, usually you will be given the choices to set QoS priority based on application, protocol, port, IP or Mac address, etc.

Question: What is Dynamic DNS (DDNS)?

Dynamic DNS allows you to have fixed domain name points to dynamic public IP, means the domain name will point to new IP when the IP is changed. This service is particular useful for hosting web server, mail server or public server in home network that use Cable/DSL broadband connection with dynamic public Internet IP, then the Internet users can just connect to your dynamic DNS and don’t worry about the public Internet IP change.

Usually you will need to have small DDNS update client installed on your computer in order to notify the DDNS server when there is public IP change. If you router supports this DDNS client feature, then you can just enable this feature on router and don't need that DDNS update client.

The examples of Dynamic DNS service providers are www.dyndns.org and www.tzo.com.

Question: What is the difference between Cable and DSL Internet connection?

Cable and DSL Internet connection are popular broadband technology that utilizes unused bandwidth over existing phone infrastructure.

Here are some differences between these 2 technologies:

The Cable connection uses shared cable to provide service in the residential area, whereas each DSL user has dedicated connection to nearest ISP’s central office.

DSL connection tends to be cheaper than Cable connection, as different DSL technology (ADSL, SDSL, HDSL, VDSL, etc) are available for service provider to roll out different packages with different prices and bandwidths. For home users, ADSL is popular Internet connection.

The bandwidth that can be offered by Cable is higher than DSL in theory, but the Cable connection is shared with many home users, so the network performance would be dropped when there are many connected Cable users. For ADSL users, you can usually get good bandwidth if you are closer to ISP’s central Office with quality link.

Question: What is Voice over IP (VoIP)?

Voice over Internel Protocol (VoIP) protocol provides alternative way for you to place phone call over IP based network or Internet instead of traditional PABX phone system. It’s cheaper to make long distance phone call this way if you compare to traditional way. When you talk by using VoIP phone, the analog data (voice) will be converted to digital data and transmitted over the Internet to the recipient.

As an example, Skype is a very popular VoIP software that let you to place call to other Skype user or phones over Internet.



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