Topic 5 - DNS Flashcards
What protocol and port number does DNS use?
UDP
Port 53
Two types of DNS lookups?
Forward lookup - the host asks about a domain name and an IP address is returned
Reverse lookup - the host asks about an IP address and a domain name is returned
Default least time on DHCP server.
1 day
What Interface does Cisco IOS DHCP relay agent supports?
unnumbered interfaces
Which Cisco IOS command will indicate that interface GigabitEthernet 0/0 is configured via DHCP?
show ip interface GigabitEthernet 0/0
Which statement about the nature of NAT overload is true?
applies a one-to-many relationship to internal IP addresses
command can you enter to display duplicate IP addresses that the DHCP server assigns?
show ip dhcp conflict 10.0.2.12
DHCP relay
DHCP relay agent is any host that forwards DHCP packets between clients and servers.
DHCP Client
Cisco IOS DHCP client enables a device to obtain an IP address from a DHCP Server dynamically using the DHCP protocol.
DHCP Server
Cisco IOS DHCP Server feature is a full DHCP Server implementation that assigns and manages IP addresses from specified address pools within the router to DHCP clients.
What are the details does DHCP offer message contain?
IP address
Domain name
lease
What type of message are DHCP DISCOVER and DHCP OFFER?
DHCP DISCOVER - Broadcast Message
and
DHCP OFFER - Unicast Message.
DHCP protocol standard?
RFC 2131
What TFTP is used to identify an external server that will be used to store the DHCP bindings database.
TFTP 150
is HSRP a Cisco proprietary protocol?
YES
Explain HSRP
Hot Standby Routing Protocol (HSRP) enables high availability by providing multiple default gateways with the same virtual IP address to hosts on a LAN.
Default priority on a HSRP?
Default priority is 100.
Remember highest number represents the highest priority
Range of HSRP
1 to 255
Preamble on HSRP
If preemption is enabled, the router with the highest priority becomes the active router
If priorities are equal, the current active router does not change
What multicast address does HSRP v1 uses to send hello packet?
224.0.0.2
What multicast address does HSRP v2 uses to send hello packet?
224.0.0.102
Group of HSRP V1 and V2
V1 is 0 to 255
V2 is 0 to 4095
what happens when an interface running HSRP 1 gets an packet from HSRP 2?
Packet is ignore
Command to see real-time Translation on the router?
Debug ip nat
Command to show all the translation?
Show ip nat translations
3 methods of NAT
1 - Static
2 - Dynamic
3 - Overload
PAT address translation also called as?
NAT Overload
Explain NAT?
Network Address Translation (NAT) is used to map private IP addresses on a LAN to a public IP address(es) on the outside interface of the router
The interface of the router connecting to the LAN network is?
NAT #ip nat inside
The interface of the router connecting to the WAN is?
NAT Outside #ip nat outside
Explain PAT?
Port-address translation
Commonly used for overloading.
An extension to NAT that permits multiple IP addresses on a LAN to be mapped to a single public IP address
What is the local IP address of a private host on your network (e.g., a workstation’s IP address) called?
Inside Local
What is the public IP address that the outside network sees as the IP address of your local host called?
Inside Global
What is the local IP address from the private network, which your local host sees as the IP address of the remote host. called?
Outside local
Explain NTP ?
The Network Time Protocol (NTP) synchronizes the time of day among a set of distributed time servers and clients
What transport protocol does NTP use?
UDP
What used in NTP to describe the distance between a device and the time source?
Stratum
What is a disadvantage of NAT?
There is no end-to-end addressing.
The Inside Local address is usually what?
An RFC 1918 address
Which type of NAT maps a single inside local address to a single inside global address?
static
The four steps in obtaining a lease are?
1 - DHCPDISCOVER
2 - DHCPOFFER
3 - DHCPREQUEST
4 - DHCPACK (if success)
The DHCPv6 REPLY packet is what type? (broadcast, multicast, unicast)
Unicast
What is dynamic NAT?
- Automatically map IP to IP
- Typically a pool of available address
What is Overloading NAT?
- Automatically map many IPs to one IP
- Uses ports to track individuals from many
___________specifies allowed IP for NAT rule
Access List
