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Flashcards

DHCP Service

Tunds System Admin Semester 2 Inglês 45 flashcards

Flashcards do conjunto (45)

  1. 1What does DHCP stand forDynamic Host Configuration Protocol
  2. 2What is DHCP used forAssigning and configuring IP address to interfaces on the network
  3. 3Give 4 examples of IP parameters on the network*IP Address
    *Subnet mask
    *Default gateway address
    *DNS server addresses
  4. 4What do you need in order to use DHCP*IP Address
    *Subnet mask
    *Lease time
  5. 5Does DHCP operate differently with IPv4 & IPv6Yes
  6. 6How does DHCP operate in IPv4*Clients need configuring to enable them to work on routed networks
    *There aren't many IP addresses so you need to manage them carefully
  7. 7How does DHCP operate in IPv6*Clients are capable of Stateless Address Auto-Configuration, so they can give themselves an IP address
    *There isn't an issue with managing IP addresses since there are loads
    *DHCP is seen as being for connecting devices not clients
  8. 8What must a host do in order to get an IP address ?It must ask a DHCP server to provide it with one
  9. 9What type of process is a DHCP and what must the host have in order to use DHCPClient/Server and it must be configured for automatic configuration
  10. 10How does a Home computer use DHCPIt uses wifi or wireless to request an IP configuration from a wireless router with DHCP functionality
  11. 11How does a work computer use DHCPIt uses a wired connection to request an IP configuration from a DHCP server
  12. 12What is sent to the Host when performing an IP configuring*IP Address
    *Subnet Mask
    *Default Gateway
  13. 13If a user with a laptop went to different networks would it automatically receive an IP configurationYes
  14. 14If a user with a laptop went to a network with no DHCP would they automatically receive an IP configurationNo they would have to configure this themselves which could lead to mistakes
  15. 15Why would a network want to re-allocate and IP addressSo that it's easier for a device to reconnect to the network prevent multiple devices from having the same IP Addresses
  16. 16What are the 3 modes of operation when assigning IP Addresses*Dynamic
    *Automatic
    *Static
  17. 17Explain what a Dynamic IP Configuration isIt's when a IP Addresses is given to a client for a time period aka lease period. If the client doesn't renew the lease during the period of time the server can claim back the IP Address and give it to another client
  18. 18Explain what a Automatic IP Configuration isIt's where IP Addresses are assigned to clients permanently. The lease period is infinite. The server maintains tables of assignments so it can re-assign a previous address to a returning client.
  19. 19Explain what a Static IP Configuration isIt's when IP Addresses are associated with a specific MAC Address. This is useful for network servers whose IP address shouldn't change.
  20. 20What does MAC address stand for and what is it ?Media Access Control and its the Physical address of the computer (Network Card)
  21. 21What are the issues with Static IP ConfigurationIf the IP Address does change you need to reconfigure it with the correct MAC Address since the MAC Addresses are not stored on the server
  22. 22What are 3 possible other names for Static IP Configuration*Fixed-address assignment
    *DHCP reservation
    *Static DHCP
    *IP Reservation
    *MAC/IP binding
  23. 23Explain what a Manual IP Configuration isDHCP servers don't have a manual mode. It's when you decide your device isn't going to be a DHCP Client and you have set up IP configuration yourself.
  24. 24How many stages will new DHCP client have to go through for IP configuration4
  25. 25Explain the process in DHCP DiscoveryIf the client is new it must find a DHCP server to give it configuration.
    It does this by sending a DHCPDISCOVER packet out on the network.
    Since it doesn't have an IP the source IP address is 255.255.255.255 and the Destination IP address is 0.0.0.0.
    In order for this to work they need to know the IP address of the DHCP server in which they should relay the request.
  26. 26Explain the process in DHCP OfferDHCP servers who receive the DHCPDISCOVER packet from a potential client will then take a look at the packet.
    It will consider if there isn't a pool or address available and an address as well if there is it will reserve an IP address and send out a DHCPOFFER packet with the IP Address, associated subnet mask and lease duration.
    The client doesn't have an IP address yet so it needs to make another broadcast as well as the server using it's own IP Address for the source IP Address of the client.
    If the DHCP server is directly connected to the clients subnet it will know which pool of addresses to look from for the NetID of its own interface. But if the packet is forwarded via router then the router will have information on the NetID of the subnet from which the packet came.
  27. 27Explain the process in Client acceptThe client accepts the first DHCP offer that it receives. But a DCHPREQUEST packet the client sends to accept the offer is still broadcasted to ender that all DHCP servers know the offer has been accepted.
    All the DHCP servers who's offers weren't accepted remove the temporary reservation and puts this back into the pool.
    The client now has an IP address in the source field
  28. 28Explain the process in DHCP AcknowledgementThe DHCP server which was accepted now sends a DHCPACK to let the client know it's acknowledged that it accepted the offer.
    This packet will include confirmation of IP Address, send lease duration and any other configuration information.
  29. 29Unless the lease period is infinite what must clients do with there IP address configurationRenew it
  30. 30What are the 2 ways to renew IP address allocation address*On restart
    *Periodic renewal
  31. 31Explain the process on restart*Whenever a client is rebooted it will try and renew its lease by sending a ancient DHCPRENEW packet to the server
    If the server and requested IP address is available it will respond with a DHCPACK confirming the address and new lease end time
    If the server cannot be contacted but the current lease is still ‘in date’ the client continues to use its current configuration
    If the lease does eventually run out then the client has to go through the whole leasing process from the beginning
  32. 32Explain the process with periodic renewalClients that are ‘up’ all the time will go through the renewal process part way through the period of the lease (eg ½ way through the lease period)
    If the lease cannot be renewed they will try again closer to the time (eg ¾ of the lease period), and so on
    If the lease cannot be renewed then the client has to go through the whole leasing process from the beginning
  33. 33What is releasing a DHCP addressIt's releasing a DHCP assigned address allows that address to be re-used elsewhere
  34. 34What are the two ways to release the packets*Automatically
    *Manually
  35. 35What is involved in Automatic releaseWhen the client shutsdown it sends a DHCPRELEASE packet to the server
  36. 36What is involved in Manual releaseWhen you use the command ipconfig utility to release this from the server
  37. 37What is a DHCP ScopeA scope is a pool of addresses on a single subnet that a DHCP server can hand out to potential clients
  38. 38Give 3 pieces of information associated with DHCP serverRouter (default gateway)
    Time Server
    Domain Name Server
    Domain Name
    Default IP Time To Live
    Static routes
    Mail server
  39. 39Give 3 pieces of information associated with DHCP ScopesNetID
    Subnet mask
    IP address range
    Lease duration
    Scope name
    Exclusion range (optional)
  40. 40What are organising options ?Options are additional information given to clients. Options may be linked to different levels within the DHCP server
  41. 41Give the 4 Organising options*Server
    *Scope (within server)
    *Class (within scope)
    *Reservation (within scope)
  42. 42Explain what is included in ServerOptions at this level apply to all scopes defined by the server
  43. 43Explain what is included in Scope (within Server)Options at this level apply to the specified scope and take precedence over options at server level
  44. 44Explain what is included in Class (within Scope)Options at this level apply to the specified class (type of client) and take precedence over options at scope and server level
  45. 45Explain what is included in Reservation (within Server)Reservations assign a specific IP address to an NIC with a specific MAC address. Options at this level apply to the specified reservation within the scope and take precedence over options at scope, server and class level

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Lecture slide 12
Criado por
Tunds
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11
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