Test 3 Flashcards
IP addresses are __-bit numbers divided into four _-bit values called octets, each octet can have a value from _ to ___
IP addresses are 32-bit numbers divided into four 8-bit values called octets, each octet can have a value from 0 to 255
Subnet masks are also __-bit numbers, that serve to determine how many bits are allocated to a ___ __, and how many are allocated to a ___ __
Subnet masks are also 32-bit numbers, that serve to determine how many bits are allocated to a network ID, and how many are allocated to a host ID
192.168.14.250 = 11000000.10101000.0001110.11111010 255.255.255.0 = 11111111.11111111.11111111.00000000
192.168.14.250 = 11000000.10101000.0001110.11111010 255.255.255.0 = 11111111.11111111.11111111.00000000
How is the subnet mask used to determine the network ID?
Computers determine the network ID by doing a logical AND operation between its IP address and subnet mask. A logical AND is an operation between two binary values. AND operations can have the following results: 0 AND 0 = 0 1 AND 0 = 0 0 AND 1 = 0 1 AND 1 = 1 The logical AND operation between a computer’s IP address and subnet mask looks like this: 10101100.00011111.01100100.00000110 (binary for 172.31.100.6) AND 11111111.11111111.00000000.00000000 (binary for 255.255.0.0) ____________________________ 10101100.00011111.00000000.00000000 (binary for 172.31.0.0)
How do i convert 125 from Decimal to Binary
To convert 125 to binary use the following chart and follow the directions: 128_64_32_16_8_4_2_1 0___1__1___1__1_1_0_1 125 is less than 128, so you place a 0 in the column under the 128. The test number remains 125 125 is greater than 64, so you place a 1 in the column under the 64 and subtract 64 from 125, leaving your new test number as 61 61 is greater than 32, so you place a 1 in the column under the 32 and subtract 32 from 61, leaving your new test number as 29 29 is greater than 16, so you place a 1 in the column under the 16 and subtract 16 from 29, leaving your new test number as 13
Converting Binary to Decimal the Simplest way: 11010011
Using the binary number 11010011, you get the following: 128+64+0+16+0+0+2+1 = 211
What is IP Address class A
- Value of the first octet is between 1 and 127
- IP registry assigns the first octet, leaving the last three octets to be assigned to hosts
- Intended for large corporations and government
What is IP Address class B
- Value of the first octet is between 128 and 191
- IP registry assigns the first two octets, leaving the third and fourth octets to be assigned to hosts
- Intended for use in medium to large networks
What is IP Address class C
- Value of the first octet is between 192 and 223
- IP address registry assigns the first three octets
- These networks are limited to 254 hosts per network
- Intended for small networks
What is IP Address class D
- Value of the first octet is between 224 and 239
- reserved for multicasting
What is IP Address class E
- Value of the first octet is between 240 and 255
- Reserved for experimental use and can’t be used for address assignment
What are reserved addresses?
Which addresses are reserved?
Addresses that can’t be routed except for the specific entities that have them reserved.
- Class A addresses beginning with 10
- Class B addresses from 172.16 to 172.31
- Class C addresses from 192.168.0 to 192.168.255
What is a link-local address
- Not assigned locally or through DHCP
- Assigned automatically when a computer is configured to receive an IP address through DHCP but no DHCP service is available
What is Automatic Private IP Addresssing (APIPA)
- This is another term for a link-local address
- assigned in the range of 169.254.1.0 through 169.254.254.255 with a subnet mask of 255.255.0.0
What is Classless Interdomain Routing (CIDR)
The use of IP addresses without requiring the default subnet mask
what is Classful addressing
The use of IP addresses with their default subnet masks
With CIDR if the IP address is 172.31.210.10 and the subnet mask is 255.255.255.0 what is the host ID?
.10
What is the format for CIDR notation
A.B.C.D/n where n is the number of 1 bits in the subnet mask
Express 172.31.210.10 with a subnet mask of 255.255.255.0 as a CIDR notation
172.31.210.10/24
The network ID is 24 bits, leaving 8 bits for the host ID
What does a broadcast domain define
which devices must receive a packet that is broadcast by another device inside the domain
TCP/IP communication relies heavily on broadcast packets, specifically which two protocols?
DHCP and ARP which both use broadcasts to perform their tasks
What is subnetting
What are the reasons to subnet
A process that reallocates bits from an IP address’s host portion to the network portion, creating multiple smaller address spaces
- To divide a very large network into many smaller subnetworks
- To conserve IP addresses
- To divide a network into smaller groups
What is the process for subnetting
- Decide how many subnets you need. Each router interface connection indicates a required subnet
- Decide how many bits you need to meet or exceed the number of required subnets
- Use the formula 2^n with n representing the number of bits you must reallocate from the host ID to the network ID
- The number of subents you create is always a power of 2, so if you need 60 subnets, you must must reallocate 6 bits (2^6 = 64) because reallocating 5 bits gives you only 32 subnets
What is supernetting
- This is the process of reallocating bits from the network portion of an IP address to the host portion
- Making two or more smaller subnets a larger supernet
- Also known as route aggregation or route summarization
Rules for IPv4 Address assignment
- A host can be assigned only a Class A, Class B, or Class C address
- Every IP address configuration must have a subnet mask
- All hosts on the same physical network must share the same network ID in their IP addresses
- All host IDs on the same network must be unique
- You can’t assign an IP address in which all the host ID bits are binary 0
- You can’t assign an IP address in which all the host ID bits are binary 1
- Computers assigned different network IDs can communicate only if a router is present to forward packets
- The default gateway address assigned to a computer must have the same network ID as that computer
Windows OSs allow multiple IP addresses to be assigned to a single network connection, via advanced TCP/IP settings box.
Why might multiple IP addresses be useful?
- The computer is hosting a service that must be accessed by using different addresses
- The computer is connected to a physical network that hosts multiple IP networks
What is a multihomed server?
What are the reasons for using this type of configuration?
- A server that has two or more NICs, each attached to a different IP network
- Each NIC requires its own IP address for the network to which its connected
Reasons for this configuration include:
- A server is accessed by internal clients and external clients
- A server provides resources for computers on multiple subnets of the network
- A server is configured as a router or VPN server
What does typing the route print command prompt do?
displays the routing table and five columns of results:
Network Destination, Netmask, Gateway, Interface, Metric
What is the netsh.exe command
This command can be used for many tasks such as firewall and IP address configuration
To see a list of netsh commands, type: netsh /?
what is ipconfig
usually used to display a computers IP address settings but it can perform other tasks including:
- /all
- /release
- /renew
- /displaydns
- /flushdns
- /registerdns
what does ping do
- used to test connectivity between two computers by sending an ICMP echo request packet
- If the destination receives the packet and is able to respond it will do so with an ICMP echo reply packet
- to see all available options for the ping command type ping /?
what does arp do?
The arp command displays or makes chagnes to the Address Resolution Protocol (ARP) cache, which contains IP address - MAC address pairs
Can add static ARP entries
Some options for ARP command:
- -a, -g: displays current ARP entries
- -d: deletes ARP entries
- -s: adds a static ARP entry
what is tracert
- usually called “trace route” because it displays the route packets take between two computers
- works by sending out packets with a total TTL value starting at 1 and increases the value until the destination is reached
- Useful for troubleshooting the routing toplogy of a complex network and finding bottlenecks
- Displays the time it took to receive a reply from each router (could indicate where bottlenecks might be)
what does nslookup do?
- Used to test and troubleshoot DNS operation
- Can be used in command mode or interactive mode
- In command mode, you type nslookup host to query for the host’s address
- In interactive mode, you can simply type host to get the host’s address
- Typinga question mark at the interactive mode prompt gives a list of available options
What is NAT and what does it do
Network Address Transition
- NAT allows an organization to use private IP addresses while connected to the internet
- The NAT process translates a workstation’s private address (as a packet leaves the corporate network) into a valid public Internet address
- When data returns to the workstation, the address is translated back to the original private address
- Nat is usually handled by a network device connected to the Internet, such as a router
- Address translation is kept track of in a NAT table
What is PAT
Port Address Translation (PAT)
- Allows several hundred workstations to access the Internet with a single public Internet address
- Each packet contains source and destination IP addresses along with source and destination port numbers
- A single public IP address is used for all workstation, but different source port numbers are used for each communication session