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Technology ICT Communications & Computer Networks Resource Notes - Network Software. Network Software.
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Technology • ICT • Communications & Computer Networks • Resource Notes - Network Software
Network Software • For networked computers to communicate with each other, network software is needed. This software is called a network protocol and is a set of rules to control the communication between the computers • Rules cover items such as: • How communication will be started • How communication will be ended • How much data can be sent at one time • How will data errors be discovered • How will data errors be corrected • How will communication with the Internet will take place
Network Software • Transmission Control Protocol/Internet Protocol (TCP/IP) • The protocol used in modern networks • A number of settings must be set on each computer
Network Software • 1. IP Address • Small networks use Class C addresses (e.g. 192.168.1.1) • The first three numbers are the address of the network • The fourth number is the address of the actual computer • The computer below is computer 1 on network 192.168.1 IP Address 192.168.1.1 • E.g. In a four computer network, the IP addresses could be: • 192.168.1.1 - 192.168.1.2 - 192.168.1.3 - 192.168.1.4 • The last possible IP address is - 192.168.1.254
Network Software • 2. Subnet Mask • The subnet mask shows what class the IP address belongs to • 255.0.0.0 - Class A network • 255.255.0.0 - Class B network • 255.255.255.0 - Class C network. IP Address 192.168. 1 .1 Subnet Mask 255.255.255. 0 • Three 255’s fix the Network address • One 0 fixes the Computer address
Network Software • 3. Default Gateway • The IP address of the Router • A router is used to connect a network to the Internet • The gateway address is the address used to leave the network • The example below is the gateway address for a router connected to Eircom Broadband: • Default Gateway 192.168.1.254 • The address would be different for other ISP’s
Network Software • 4. DNS Servers • Websites are given user friendly names called URL’s • This stands for Uniform Resource Locator • Examples include - www.google.ie, www.t4.ie etc. • Computers can’t use URL’s to find websites • Computers need the IP addresses of the computers holding the websites to locate them • A DNS (Domain Name Service) server is a Database used to link the Domain name (www.t4.ie) to it’s IP address (82.195.130.32 ) etc.
Network Software • Each ISP has it’s own DNS servers • ISP’s use 2 DNS servers • If one goes offline, the other can take over (redundancy) • You can use any ISP’s DNS servers • DNS servers communicate with each other on a global scale • If a website can’t be found, a DNS error is given • The DNS servers shown below are for Eircom broadband: • Preferred DNS server:159.134.237.6 • Alternate DNS server:159.134.248.17
Network Software ISP DNS servers Below is a table with the DNS servers most commonly used in Ireland:
Network Software DNS server entries Below is a number of sample entries from a typical DNS server:
Network Software • 5. DHCP server • Stands for - Dynamic Host Configuration Protocol • Used to automatically give IP information to network devices • Dynamic - the IP information is leased and can change • The Lease length is given with the IP information • IP information set manually is called Static addressing • Dynamic addressing simplifies network administration • Software keeps track of the allocation of addresses and leases • Addresses given from a Scope - a set pool of addresses • New PC’s are easily added as the IP information necessary to join the network is automatically given
Network Software • In Workgroups, the Router usually supplies the IP information, if dynamic addressing is being used • In Domains, the Server usually provides the IP information • Typical DHCH supplied IP information is shown below: