11 - Basic Network Services Flashcards
What are the three methods of NAT?
One-to-One mapping or static nat
Many-to-Many mapping or dynamic nat
Many-to-One mapping o PAT
What is a local address as it pertains to NAT?
source or destination ip address as seen from the perspective of a host on the inside network
What is a global address as it pertains to NAT?
source or destination ip address as seen from the perspective of a host on the outside network
What is an inside local address?
ip address that represents an internal host to the inside network
What is an inside global address?
ip address that represents an internal host to the outside network
What is an outside global address?
ip address that represents an external host to the outside network
What is an outside local address?
ip address that represents an external host to the inside network
What is another name for NAT many-to-one mapping?
nat overloading
Do dynamic NAT mappings expire after a period of inactivity?
Yes
How does port address translation NAT work?
layer four port number to identify each address mapping
What command is used to configure NAT on the interface level?
ip nat inside
ip nat outside
What is the command to configure static NAT?
ip nat inside source static 192.168.1.11 2.2.2.2
What command is used to verify your NAT translations?
sh ip nat translations
what is the command to configure dynamic NAT?
ip nat pool NATPOOL 2.2.2.2 2.2.2.14
access-list 1 permit 192.168.1.0 0.0.0.255
ip nat inside source list 1 pool NATPOOL
What is the command to configure PAT?
access-list 1 permit 192.168.1.0 0.0.0.255
ip nat inside source list 1 interface fa0/0 overload
What port does DNS clients use for dns queries?
UDP 53 mainly
Does DNS use tcp?
Yes, when the query is larger than 512 bytes
What command is used on a router to translate dns hostnames into ip addresses?
ip domain lookup
you can use no ip domain lookup to prevent the cisco device from trying to translate a hostname on a mistyped word
What command is used on a router to configure your dns servers on a dns client device?
ip name-server 10.249.83.51
What is the command to enable a dns server on a cisco device?
ip dns server
What are the three different allocation methods defined by DHCP?
dynamic allocation
automatic allocation
manual allocation
What is dynamic allocation in DHCP?
assigns the host the next available ip address from the pool
What is automatic allocation in DHCP?
permanently assigns the same ip address to the same client
What is manual allocation in DHCP?
admin creates the hostname to address mapping
Describe the process when a client computer requests an ip address.
- client sends dhcpdiscover via broadcast
- server sends dhcpoffer via unicast
- client sends dhcprequest via broadcast
- server sends dhcpack via unicast
What is a dhcp discover message?
it is a broadcast packet that is sent by the client to locate a dhcp server
What is a dhcp offer message?
it is a unicast packet that is sent by the server containing the ip address, subnet mask, gateway and dns
What is a dhcp request message?
it is a broadcast packet that is sent by the client so that other dhcp servers can re-allocate the ip address offered to the client
What packet can be sent to reject the dhcpoffer from a server?
dhcpdecline broadcast packet
What is a dhcp achnowledgement message?
it is a unicast packet that is sent by the server that confirms that the ip address has been officially assigned to the client
What is the command to configure an interface as a dhcp client?
ip address dhcp
What is the command to configure a router to act as a dhcp relay?
ip helper-address 10.10.10.1
What command is used on an interface to obtain extra information from a dhcpv6 server?
ipv6 address autoconfig
What command is used to assign itself a global unicast ipv6 address using slaac?
ipv6 address autoconfig
What ipv6 command enables the stateless address configuration of an interface and inserts a default route using a specified default device?
ipv6 address autoconfig default
What is the command for an interface to be configured with an ipv6 stateful address?
ipv6 address dhcp
what command is used in ipv6 to send nonaddress information to clients?
ipv6 nd other-config-flag
What command do you use to view dhcp conflicts?
sh ip dhcp conflict
What command do you use to view the addresses that have been leased by clients?
sh ip dhcp binding
What command is used to remove a dhcp binding?
clear ip dhcp binding 10.10.10.10
or
clear ip dhcp binding *
What is used to determine the authority of an NTP server?
its stratum
What is a stratum 1 server?
one that connects to an atomic clock or gps unit
Is ntp enabled by default on cisco devices?
no
What is the command to enable ntp on a cisco device?
ntp server 10.249.83.230
How is time formatted with ntp by default?
UTC or coordinated universal time
What command can be used to adjust the time on a cisco device to match the local timezone?
clock timezone CST -6
What is the default stratum number of the ntp master command?
stratum 8
Why would you use the ntp master command?
If there is no network time source or external time source available. it will allow the device to use its internal clock
What commands can be used to verifiy ntp?
sh ntp associations or
sh ntp status
What command is used for the cisco device to use its internal clock for ntp?
ntp master (with no stratum number)
