Hostname and IP Address

Size: px

Start display at page:

Download "Hostname and IP Address"

Gavin Kelley
5 years ago
Views:

1 1/19 IP Addressing Surasak Sanguanpong Last updated: 27 June 2002 Hostname and IP Address 2/19 browser What is the IP address of is Packets for DNS Each node is assigned with a name and address A DNS reponds to the name-to IP address mapping The IP address is used by the client to create packets with IP destination address ( )

2 IP Address 3/19 32 bits bits 8 bits 8 bits 8 bits written in decimal form with decimal points (Dot-decimal Notation) A 32 bit address that uniquely identifies a node Two devices can never have the same address The dot notation is easily for reading and writing IP Address with router 4/19 An IP address is associated with an interface (not a machine)

3 Addressing concept 5/19 Partitions address into 2 fields Network address (define a network) Node address (specific a device on the network) network 1 network network 3 IP Addressing 6/19 8,16, 24 bits from NIC Network 32 bits Host Identify a host Identify a network

4 IP Address Class 7/ Class A 0 Network ID Host ID Class B 10 Network ID Host ID Class C 110 Network ID Host ID Class D 1110 Multicast Address Class E Reserved Note: No Network ID and Host ID on Class D and Class E IP Address Network 8/19 Class A to Class B 0 to to Class C 128 to to to to to to 255 Class D Class E

5 Number of Networks and Hosts 9/19 Class Number of Networks Number of Hosts A B C D E 2 7-2= =16, =2,097,152 Not applicable Not applicable =16,277, =65, =254 Not applicable Not applicable Special Addresses 10/19 Reserved addresses that are not allowed to be assigned to any node NetID any any All 1s All 0s 127 HostID All 0s All 1s All 1s All 0s any Purpose Network Address Directed Broadcast Address Limited Broadcast Address This host on this network Loopback Address

6 Network Address : Example 11/19 Class A Class B Network Broadcast Network Broadcast : Class C Network Broadcast : Directed Broadcast Address 12/ Directed Broadcast Address Broadcast to a specific subnet Router forwards directed broadcast address to the subnet

7 Limited Broadcast Address : Example 13/ Limited Broadcast Address Broadcast to all hosts on my network Router blocks limited broadcast address to the subnet Note : An class E address This host on this network Address 14/19 Bootstrap Server A diskless client uses as a source address for requesting a service from a bootstrap server class A address Source : Destination : class E address is also used by routers to advertise the default route

8 Loopback Address 15/19 Process A Process B TCP/UDP IP Loopback driver Datalink Physical Pseudo interface that allows a host to use IP to talk to its own services Most system assign the IP address of and assign it the name localhost A packet that has been sent to loopback address never leaves the machine Private Address Space 16/19 Class A B C Networks to to Number RFC 1918 defines special IP address blocks of Class A, B and C that will be isolated from the Internet Any organization can use any address from this set without any permission. Purposes : Experiment or isolated network Internal Security

9 ifconfig See your IP address and subnet mask with Unix s interface configuration command : $ ifconfig -a lo Link encap:local Loopback inet addr: Bcast: Mask: UP BROADCAST LOOPBACK RUNNING MTU:3584 Metric:1 RX packets:4849 errors:0 dropped:0 overruns:0 frame:0 TX packets:4849 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 eth0 Link encap:ethernet HWaddr 00:10:4B:13:0A:BC inet addr: Bcast: Mask: UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets: errors:0 dropped:0 overruns:0 frame:0 TX packets: errors:0 dropped:0 overruns:0 carrier:0 collisions:0 Interrupt:10 Base address:0xb800 17/19 Problems with Class assignment 18/19 Class A takes 50% range, class B 25%, class C 12.5% These lead to : address wasteful (specially in class A) running out of IP address A B C D E

10 19/19 HOW IR assigns IP address (RFC1466) Class A : no allocations will be made at this time Class B : allocations will be restricted. To apply: organization presents a subnetting more than 32 subnets organization has more than 4096 hosts Class C : divided into allocated blocks to distributed regional Multi-regional Europe Others North America Central/South America Pacific Rim Others Others IANA reserved

Computer Network Addressing. The TCP/IP Layers and Addresses. Topics. The Internet Communication. The TCP/IP Layers and Addresses IP Address

Computer Network Addressing. The TCP/IP Layers and Addresses. Topics. The Internet Communication. The TCP/IP Layers and Addresses IP Address Topics Computer Addressing The / Layers and Addresses Computer and Data Communication Laboratory I 2 The Internet Communication The / Layers and Addresses 4 Protocol Layers / Protocol Stack OSI and / SMTP