The DNS server can be a public server or the gateway address. If it is the gateway address, the DNS server address should be configured on the gateway. The DNS server should also be configured on the users TCP/IP adapter.
Physical Address: It’s called as MAC Address (48 bit)
Logical Address : It’s Called as Ip Address (IPv4 -32 bit & IPv6 -128 bit)
Its used to connect same type of devices without using a switch/hub so that they can communicate.
Check the IP connectivity with the DHCP server from a system configured on the network. Test if the DHCP client and server service is started on the DHCP server and the client. Test if the DHCP server service is reachable using nmap.
IPCONFIG command is used to display the IP information assigned to a computer.
From the output we can find out the IP address, DNS IP address, gateway IP address assigned to that computer.
Public IP addresses:
A public IP address is any valid address, or number, that can be accessed over the Internet. Internet standards groups, such as the Network Information Center (NIC) or the Internet Assigned Numbers Authority (IANA), are the organizations responsible for registering IP ranges and assigning them to organizations, such as Internet Service Providers (ISPs).
Private IP addresses:
A private IP address is any number or address assigned to a device on a private TCP/IP Local Area Network that is accessible only within the Local Area Network. For a resource inside the Local Area Network to be accessible over the Internet, a device within the Local Area Network must be connected to the Internet with a public IP address, and the networking must be appropriately configured.
The same Internet standards organizations have reserved the following three IP address ranges that will never be registered publicly:
First IP in block Last IP in block
Check the IP connectivity using ping. Check if port 23 is open on the router using nmap.
1.Straight Crimping : Communication bw the Difference Devices
Ex.( System To Switch & Switch to System or Modem)
2.Cross Crimping : Communication bw the same Devices
Ex.( System To system & Switch to switch)
Check the connectivity with the default gateway. Check if the DNS server is configured on the PC. Check if the appropriate port number is active using nmap on the DNS server.
ClassA : 1-126 N.H.H.H 188.8.131.52 to184.108.40.206 - 16 million hosts on each of 127 networks.
ClassB : 128 -191 N.N.H.H 1 220.127.116.11 to18.104.22.168 - 65,000 hosts on each of 16,000 networks.
ClassC: 192- 223 N.N.N.H 22.214.171.124 to126.96.36.199 - 254 hosts on each of 2 million networks.
ClassD : 224-239 - Reserved for multicast groups.
ClassE: 240-254 - Reserved for future use.
Ranges 127.x.x.x are reserved for loopback or local host
Range of 169.254.X.X is APIPA, stands for automatic private IP addressing
Hub (layer 1 Device):
Switch (layer 2 Device)::
In networks, a device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2) and sometimes the network layer(layer 3) of the OSI Reference Model .
Router (layer 3 Device):
A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP [Network Layer (Layer3)]
Subnet mask is used for identify the Network.
For a class A address, a standard subnet mask is 255.0.0.0,
For a class B address, a standard subnet mask is 255.255.0.0,
For a class C address, a standard subnet mask is 255.255.255.0.
Test basic connectivity with ping, Check with nmap if the ports are open (20 and 21). Check if a firewall is restricting traffic to the server.
When DHCP server is not available the Windows client computer assignes an automatic IP address to itself so that it can communicate with the network cmputers. This ip address is called APIPA. ITs in the range of 169.254.0.0 to 169.254.255.255
APIPA stands for Automatic private IP addressing.
A default gateway is a routing device used to forward all traffic that is not addressed to a destination within the local network or local subnet. If you don’t have a default gateway, it is not possible to communicate with the network device/host of different networks.
Domain is created when we install Active Directory. It's a security boundary which is used to manage computers inside the boundary. Domain can be used to centrally administor computers and we can govern them using common policies called group policies. We can't do the same with workgroup.
Domain: Collecton of clients controlled by the server called Domain
Work Group : Colletion of Client network called Work Group
The theoretical length is 100 meters but after 80 meters you may see drop in speed due to loss of signal.
Ping the DNS server and check the response. Check with wireshark if DNS request and response packets are being sent and received.
PING: Packet Internet Gropper. It's a diagnostic utility, which diagnose connectivitybetween computers. It use ICMP: Internet Control Messaging protocol to send echorequests ( usually 4 packets) and receive echo replies (4 packets)