Flashcards
Network Layer
Flashcards do conjunto (43)
- 1Which layer is concerned with getting packets from source to destination?Network
- 2What shields the transport layer from the subnet?Network layer
- 3Which layer has repeaters or hubs?Physical
- 4Which layer has bridges or switches? for minor protocol translationData-link layer
- 5What are two Switched networks?Circuit-switched and packet-switched
- 6What are two connections Packet-switched networks can haveConnectionless and connection-orientated
- 7What protocol is responsbile for transporting datagrams/packetsInternet Protocol
- 8What does TCP provideend-to-end communication
Flow control through a numbering system
Error control
Congestion control - 9Name the TCP/IP modelApplication
Transport
Internet
Host-to-Network - 10What does an IP address refer to?A Network interface
- 11Difference of IPv4 and IPv6IPv4 is 32 bits in length 2^5
IPv6 is 128 bits in length 2^6
IPv6 in various stages of development - 12IPv4 is what kind of addressing?Dotted decimal to binary notation
117.149.29.2
to
01110101 10010101 00011101 00000010 - 13Number of networks and hosts for A B CA - 2^7 networks and 2^24 hosts
B - 2^14 networks and 2 ^16 hosts
C - 2^21 networks and 2^8 hosts - 14Problems with class AA is too large for almost any organisation
- 15Problems with class BIs also too large for most organisations
- 16Problems with class CC is too small for most organisations
- 17What is classless addressingIt was introduced to give more organisations access to the internet, instead of working with classes, we work with address blocks. Each entity is given a block of addresses to suit the needs
- 18Restrictions with Classless addressingAddress must be in contiguous blocks
The number of addresses provided must be a power of 2
The first address must be evenly divisible by the number of addresses - 19If a company was granted with a block of 16 addresses. how would you ensure that the addresses were valid?The addresses are contiguous
The number of addresses is a power of 2, so 2^4 = 16 so thats good
The first address is divisible by 16, so convert to decimal. - 20How are IPv4 classess address defined?x.y.z.t/n
- 21If you have 16 hosts, thats 2^4 the last bits for the first CIDR mask must be 4 0's. what must the lad address have as the last 4 bits?1111
- 22Which default classful network has this binary mask 11111111 11111111 00000000 00000000B
- 23Whats wrong with IPv4?Only 4.3 billion unique IP addresses, compared to IPv6.
340,000,000,000,000,000,000,000,000,000,000,000,000 - 24What is tunneling?Used when two machines wish to communicate with each other where the packet must pass through an IPv4 network when both hosts are IPv6
- 25What is header translation?Will be performed when majority of the internet is IPv6. The header is translated from IPv6 to IPv4
- 26What format are IPv6 addresses usually formatted?Hexadecimal
- 27How do you work out the number of IP addresses from 17.12.40.0 /262^(32-26) = 64 addresses
so :
17.12.40.0 - 17.12.40.63 - 28If you have a start IP of 17.12.14.0 /26 and an end ip of 17.12.14.63 /26 if M1 had 32 addresses how would you work this out?log2(32) = 5
32-x = 5
32 - 27
m1 = 27 - 29What is ICMPInternet Control Message Protocol
- 30What is ARPAddress resolution protocol
- 31What is RARPReverse Address Resolution Protocol
- 32What is BOOTPBooststrap Protocol
- 33What is DHCPDynamic host configuration protocol
- 34What is IGMPInternet group Management protocol
- 35What is static mapping?A table stored on each machine
mapping from logical to physical address
- limitations:
A machine could change its NIC
A mobile device can roam between networks resulting in a change to the physical address - 36What is dynamic mapping?When a machine know either or both of the addresses ( logical or physical ) it can use a protocol to find the other one
- 37What is address resolution protocol?ARP provides a dynamic mapping from logical to physical address
An ARP query packet is sent from the host or router and broadcasted on the network.
Only the intended recipient recognises its own IP address and responds to the ARP with an ARP response packet. Once the response reaches the sender packets can be sent over the network - 38How often do ARP requests have to be made?ARP mappings are kept in cache memory for 20-30 minutes
- 39What is BOOTP and what does it doBootstrap Protocol
Replacement to RARP
An application layer protocol
Introduces the use of a relay agent allowing packets to be forwarded from the LAN using standard routing - 40What is DHCP and what does it do?Dynamic Host configuration protocol:
- Provides static and dynamic address allocation
- Can also allow for manual or automatic configuration
-DHCP allows for static addresses to be created manually but also dynamic addresses to be created automatically - 41What is ICMP and what does it do?ICMP messages are a mechanism for reporting any transmission errors back to the sender
The ICMP message is encapsulated in the IP packet
ICMP is the basis for ping and traceroute
ICMP produces two types of messages:
Error-reporting messages
Query messages - 42Where is ICMP used?The ping command is used to find out if a host is alive and responding
- The source sends an ICMP echo-request message
- Each packet gives a RTT in milliseconds - 43What is the Internet group management protocol and what does it do?- Internet protocol can use unicast one to one and many to many.
In a network, there are one or more routers that can distribute multicast packets. IGMP packets provide information about the status of memberships of groups (hosts or routers) connected to the network.
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- FlashCards sobre Network Layer, criado por Luke Garrigan em 06-05-2016.
- Criado por
- Luke Garrigan
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