1. Technology ICT Communications & Computer Networks Resource Notes - Network Software

2. 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

3. 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

4. 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 Address192.168.1.1 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

5. 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.  Three 255’s fix the Network address  One 0 fixes the Computer address IP Address192.168. 1.1 Subnet Mask255.255.255. 0

6. 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 Gateway192.168.1.254  The address would be different for other ISP’s

7. 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.

8. 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

9. Network Software ISP DNS servers Below is a table with the DNS servers most commonly used in Ireland: ISPDNS Servers Eircom159.134.237.6 - 159.134.248.17 Digiweb83.147.160.2 - 83.147.160.3 Net 180.249.249.249 - 80.249.249.250 BT Ireland194.125.2.240 - 194.125.2.241 Heanet87.32.4.16 - 87.32.4.24

10. Network Software DNS server entries Below is a number of sample entries from a typical DNS server: URLIP Address www.google.ie216.239.59.103 www.microsoft.com65.55.21.250 www.mozilla.com63.245.213.11

11. 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

12. 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: