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System Admin- IP Addressing
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- 1What is the most significant difference between IPv4 and IPv6?is the number of unique IP addresses possible
- 2the major differences between IPv4 and IPv6?1. address length- IPv4 only has 32 bit addresses, IPv6 has 128 bit addresses
2. address auto-configuration- IPv6 hosts can configure themselves to work on a routed network, IPv4 hosts are unable to do this.
3. multicast vs broadcast- IPv6 can use multicast when IPv4 would have used broadcast. Multicast is a more efficient use of bandwidth.
4. Security- Network layer is mandatory in IPv6 but optional in IPv4.
5. Simplified Processing- IPv6 header is simpler than that for IPv4 and the processing required by routers has also been simplified resulting in more efficient processing. - 3What is IP addressing?an end-station global addressing format used within the TCP/IP protocol suite
- 4what was the TCP/IP suite designed for?use over heterogeneous data communications networks - ie it doesnt matter what the underlying networks are they can be connected. used over the internet and in many smaller networks. TCP/IP protocols cover layers 3-7 of the OSI reference model.
- 5what are IPv4 addresses?32 bit numbers, each IP address has two parts: a NetID and a HostID
Net ID= identifies the part of the network the host is connected to
Host ID= identifies a specific host on that part of the network
NetID always the first part of the IP address and HostID the last part - 6what are the 3 classes of unique IP addresses in Classful IPv4 addressing?CLASS A- First 8 bits are NetID, first bit is always 0
CLASS B- First 16 bits are NetID, first two bits are always 10
CLASS C-First 24 bits are NetID, first three bits are always 110 - 7what is a subnet mask?a 32 bit number associated with an IP address, it works like this:
- a "1" in the subnet mask indicates that the equivalent bit in the IP address is part of the "NETID"
-a "0" in the subnet mask indicates that the equivalent bit in the IP address is part of the "HOSTID" - 8e.g. of subnet maskA subnet mask of: 11111111000000000000000000000000
indicates: first 8 bits of the associated IP address are NetID bits remaining 24 bits of the associated IP address are HostID bits.
This would be a subnet mask for a Class A IP address - 9What are IPv4 addresses presented in?System called Dotted Decimal Notation
- 10What is a Dotted Decimal Notation?Here the 32 bit IP address is broken up into 4 octets (or bytes) and each of these octets are represented by its decimal equivalent
- 11e.g of dotted decimal notation32 BIT IP ADDRESS - 01110110111101001001010010110011
Address in 4 octets- 01110110 11110100 10010100 10110011
Each octet in decimal- 118 244 148 179
DOTTED DECIMAL REPRESENTATION- 118.244.148.179
Subnet masks are also represented in dotted decimal notation - 12What is important when converting from dotted decimal notation to binary?each decimal number must be converted to an 8 BIT BINARY NUMBER, which may require padding with leading zeros e.g.:
Decimal value of= 214
in binary this is = 11010110 (already 8 numbers no padding required)
e.g. 2- Decimal = 68
binary= 1000100 ( only 7 numbers so padding of one 0 is required 01000100) - 13what are the classful subnet masks?Class A- First octet is from 0 to 126
Class B- First octet is from 128-191
Class C-First octet is from 192-223 - 14Example 1 of IP address of 17.54.213.45- value in first octet is 17 so in a class based system this is a Class A IP address
- For class A IP addresses the first 8 bits are NetID
- so in binary the subnet mask is
11111111 00000000 00000000 00000000
- in dotted decimal notation the subnet mask is 255.0.0.0 - 15Example 2 IP address of 134.214.56.2- value in First octet is 134 so this is a Class B IP Address
- For Class B IP Addresses the first 16 bits are NetID
- in binary the subnet mask is:
11111111 11111111 00000000 00000000
- in dotted decimal notation the subnet mask is:
255.255.0.0 - 16Example 3 of IP address 206.1.56.2value in first octet is 206 so is a Class C IP address
for Class C the first 24 bits are NETID
so in binary the subnet mask is 11111111 11111111 11111111 00000000
in dotted decimal the subnet mask is 255.255.255.0 - 17what is a subnet?A logical division of a network where in each subnet all end stations (hosts) have the same NetID but each has a unique HostID
- 18Subnets are connected by routers but what don't they transmit?certain types of traffic from one subnet to another e.g. broadcast traffic. A small network may only have 1 subnet and larger network may have two or more
- 19What does the NetID do?it tells a source host what subnet it is on and whether or not a destination host is on the same subnet
- 20IPv4 NetID'scomp determines NetID by applying the subnet mask to the IP address.
IPv4 NetID's always shown as 4 dotted decimal number, even though by definition only part of the IP address is NetID and octets which are the hostID parts of IP Address are represented in the NetID with a 0
e.g.
IP address= 56.234.45.67
subnet mask= 255.0.0.0
subnet mask indicates that only first octet is part of NetID so NetID= 56.0.0.0
e.g. 2
IP address= 127.89.245.21
Subnet Mask= 255.255.255.0
subnet mask indicates that first 3 octets are part of NetID so NetID=127.89.245.0 - 21rules concerning numbers used for the NetID and the HosID when you assign an IP address are:- comps on the same logical subnet must have the same NetID
- comps with the same NetID must have diffferent HostID's
- The first number in the NetID cannot be 127. This NetID is reserved for diagnostic purposes e.g. loopback testing
- The numbers in the HostID cannot be all 255's as this address is used as an IP broadcast address
- The numbers in the HostID cannot all be 0's because this address is used to denote a NetID
- No 2 subnets on the network can have the same NetID - 22subnet masks always show that?only first octet of IP address is NetID
remaining octets are HostID
e.g. 56.0.0.0 - 23What is a default gateway?For a specific host the IP address of the router that is on the same subnet as the host. All info that the host needs to send to subnets other than it's own is routed through the default gateway.
- 24Default Gateway extrasthe network card/router needs its own IP address with the same NetID as the subnet and a unique HostID
- 25Tutorial Q1: Why was IPv6 introduced and what are the major differences between IPv4 and IPv6?because the IPv4 address range has become exhausted.
the major differences between IPv4 and IPv6 are:
1. address length- IPv4 has only 32 bit IP addresses and IPv6 has 128 bit IP addresses
2. address auto configuration- IPv6 hosts can configure themselves on a routed network but IPv4 cannot do this
3. multi-cast vs broadcast- IPv6 use multicast when IPv4 would of used broadcast. multicast is a more efficient use of bandwidth
4. Security- network layer security is mandatory in IPv6 but not in IPv4
5. simplified processing- IPv6 header is much simpler than that for IPv4 and the processing required by routers has also been simplified resulting in more efficient processing. - 26Q2: what is a subnet mask for?used to explicitly identify which bits of an IP address are NetID and which bits are HostID
- 27Q3: in binary what is the subnet mask for a Class B IP address?11111111 11111111 00000000 00000000
- 28Q4: what is the IP address 0011111000010111100110100000010 in dotted decimal notion?00111110 00010111 10011010 00000010 (blocks of 8 bits)
00111110 = 62
00010111=23
10011101=157
00000010=2
dotted decimal notion - 62.23.157.2 - 29Q5: A comp has an IP address of 26.189.13.7 why is this not 11010101111011101111 in binary what should it be?because it has to be 32 bits and four 8 bit octets so 0's has not been added to pad each number from decimal to binary
it should be:
26=00011010
189= 10111101
13=00001101
7=00000111
00011010 10111101 00001101 00000111 - 30Q6: A comp has an IP address of 167.89.34.6 what class is this IP address and what is it's default class based subnet mask?Class B IP address it's default class based subnet mask is 255.255.0.0
- 31Q7: Comp A has an IP address of 165.189.231.6, Comp B has an IP address of 168.187.34.7. Are comp A and B local or remote to each other? Explain how you arrive with you answer?Assuming a class based system of B, the NetID for comp A is 165.189.0.0 and comp B is 168.187.0.0 so the NetID are different so they both are on two different subnets
- 32Q8: What is wrong with the following IP addresses?- 127.45.21.78
no address can start with 127 as this is a reversed address
- 176.34.0.0
This is an NetID not an IP address
- 210.34.21.255
is a broadcast IP address for the 210.34.21.0 subnet - 33Q9: Are the following IP Addresses valid? why or why not?-11.0.0.255
is valid because it is a class A address so the last 3 octets are HostID. These octets are neither all 0's or 255's so this is a valid address
-145.34.255.0
is valid because it is a Class B address so last 2 octets are HostID. These octets are neither all 0 or 255 so this is a valid address - 34Q10: Comp A and comp B are remote from each other, separated by a router, What info do you need to provide to each comp to allow them to communicate? why?Both comps need the IP address of the router interface connected to their subnet, so they know where to send packet for a remote destination.
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- Fichas sobre System Admin- IP Addressing, creado por Robena786 el 11/05/2015.
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