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What are the different WAN technologies?
- Leased Line
- Circuit switched
- Packet Switced
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Which WAN type is connects via a Synchronous Serial Interface?
Leased Line
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Which WAN type is Easiest to configure?
Leased Line
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Which WAN type has the Best reliability?
Leased Line
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Which WAN type is Most expensive for long distances?
Leased Line
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What are the traits of a leased line?
- Connects via a synchronous Serial Interface
- Easiest to configure
- has the best reliability
- most expensive for long distances.
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Which encapsulation methods does leased lines use?
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What is the default encapsulation for leased lines?
HDLC
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Which WAN type uses HDLC encapsulation?
- Leased Lines
- Cicuit Switched
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Which WAN types use PPP encapsulation?
- Leased Lines
- Circuit Switched
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Which WAN types use SLIP encapsulation?
- Leased Lines
- Cicuit Switched
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What are the 2 types of HDLC encapsulation breakdown?
ISO and Cisco
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What is the ISO encapsulation breakdown?
- Flag
- Address
- Control
- Data
- FCS
- Flag
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What is the Cisco HDLC breakdown?
- Flag
- Address
- Control
- Proprietary Data
- Data
- FCS
- Flag
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Which RFC identifies PPP?
1661
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What does RFC 1661 identify?
PPP
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Name the PPP sublayers.
- Network Control Protocol (NCP)
- Link Control Protocol (LCP)
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Which encapsulation method do NCP and LCP belong to?
PPP
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What is sublayer NCP of the PPP encapsulation type responsible for?
responsiblefor supporting multiple layer 3 protocols
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Name the layer 3 protocols that the sublayer NCP of the PPP encapsulation type?
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What is sublayer LCP of the PPP encapsulation type responsible for?
- establishing the link
- negotiating optional settings
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What are the components of the sublayer LCP of the PPP encapsulation?
- Compression
- Callback
- Authentication
- Multilink
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What is the purpose of compression for the sublayer LCP of the PPP encapsultion?
To conserve bandwidth across the WAN
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What are the options for compression for the sublayer LCP of the PPP encapsulation?
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What is the purpose of callback of the sublay LCP of the PPP encapsulation?
- When you dial into a router using a modem or ISDN and then disconnect. The other router then calls you back at a predefined number.
- centralized billing
- security
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What are the different methods of authentication used by the LCP sublayer of the PPP encapsulation?
CHAP and PAP
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Describe the authentication process used by CHAP for the LCP sublayer of the PPP encapsulation.
performs a three-way authentication process which takes place not only at the beginningof a connection, but also every two minutes.
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What password encryption technology does the LCP sublayer for the PPP encapsulation use?
MD5 hash
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Describe the authentication process used by PAP for the LCP sublayer of the PPP encapsulation.
uses a two-way authentication process where the username and password is sent followed by a response message indicating successful or failed authentication.
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What does mutilink of the LCP sublayer for PPP encapsulation do?
allows you to bundle together more than one link to create more bandwidth. Think ISDN
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What is the sequence of commands to configure the PPP encapsulation for leased lines and cicuit switched networks?
- hostname [select a hostname]
- username [hostname of remote router] password [select a password which must be used by both routers]
- interface serial0
- encapsulation ppp
- ppp encapsulation [pap, chap]
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What are the commands used to troubleshoot ppp encapsulation for leased lines and curcuit switched networks?
- show interfaces
- debug ppp authentication
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When using the command show interfaces for a leased line or curcuit switch connection using PPP encapsulation, What will be shown?
Shows you if the line protocol is up or down and the state of LCP
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What command will show you if a line protocol is up or down?
show interfaces
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What command will give you the LCP status for PPP encapsulation used for leased lines and curcuit switched networks?
show interfaces
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What will the debug ppp authentication command show you?
shows you your authentication as it happens
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Which command will show you your authentication as it happens for PPP encasulation used by leased lines and curcuit switched connections?
debug ppp authentication
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Which WAN technology establishes a link between 2 sites using the telephone company?
Curcuit Switch
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What does a curcuit switched network use to connect?
- modems connected to an asynchronous interface
- ISDN
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Which WAN technology uses Modems on an asynchronous interface or ISDN connection to connect?
Curcuit Switched
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What encapsulation types are used by curcuit switched WAN connections?
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What is the default encapsulation type used on a curcuit switched connection?
HDLC
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What is the most common encapsultion type used on a curcuit switched connection?
PPP
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Which WAN technology is known as a nonbroadcast multi-access (NBMA) network?
Packet Switched
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What is a NBMA network?
broadcast traffic is not allowed to traverse frame-relay traffic.
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What is a known problem with packet switched networks?
Split Horizon
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Which WAN technology has a known problem called Split Horizon?
Packet Switched
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What is the Split Horizon Rule on Packet Switched Networks?
states that a route learned on an interface should not be advertised back out that same interface
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What are the solution used for the Split Horizon rule on packet switched networks?
- Use the no ip split-horizon command
- use a fully meshed topology where every router has a PVC to every other router
- use static routes instead of dynamic routing protocols
- use subinterfaces
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What problems can be caused by using the no ip split-horizon command for packet switched networks?
it can create loops
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What is a problem with using a fully meshed topology where every router has a PVC to every other router to solve the split horizon rule for packet switched networks?
It can be very expensive.
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What is the problem with using static routes?
Static routes are never a scalable solution
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Which solution is the best solution to solve the split horizon rule for packet switched networks?
subinterfaces
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What are the encapsulation types used for Packet Switched networks?
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Which WAN technology uses frame-relay, ATM and X.25 encapsulation types?
Packet Switched
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What are the traits of a frame-relay encapsulation type for packet switched networks?
- Used as an alternative to leased lines when leased lines are too expensive
- uses a single serial interface on a router connecting to multiple sites through virtual cucuits.
- identified by Data Link Connection Identifiers (DLCI)
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When using frame-relay, What Type of virtual curcuits are available?
- Permanent Virtual Curcuit (PVC)
- Switch Virtual Curcuit (SVC)
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Which Virtual Curcuit for Frame-Relay is always on, always available and operates like a leased line?
PVC
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Which frame-relay virtual curcuit is most commonly used?
PVC
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Which frame-relay virtual Curcuit is assigned a CIR by the provider?
PVC
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What is a CIR that is used by the PVC frame-relay virtual curcuit?
the guaranteed rate at which you are allowed to pass data for a particular PVC
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When are you allowed to burst above the CIR on a PVC virtual frame-relay connection?
When there is no congestion on your link
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When using a PVC virtual frame-relay circuit, how is the data treated the goes above the CIR?
It is marked as DE (discard eligible) and if there is no congestion it will pass through, but if there is congestion, it will be discarded.
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What actions are taken by the provider when there is congestion on a PVC virtual Frame-relay curuit?
congestion notification messages are sent out to notify both the sending and the receiving routers that congestion has occurred and that they should slow down their transmission rates.
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What is a Backward Explicit Congestion Notification (BECN) used by a provider for PVC frame-relay networks?
a congestion notification message sent back to the sender to slow down transmission rates.
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What is the term used that describes a congestion notification message sent back to the sender to slow down transmission rates?
BECN
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What is a Forward Explicit Congestion Notification (BECN) used by a provider for PVC frame-relay networks?
a congestion notification message sent forward to the destination to slow down transmission rates.
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What is the term used that describes a congestion notification message sent forward to the destination to slow down transmission rates?
FECN
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Which Frame-Relay Virtual Cicruit is established only when needed?
SVC
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What is a frame-relay DLCI?
a number assigned by your provider and is used to identify your router by the frame-relay provider.
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What is the router identifier called that is used by your frame relay service provider?
DLCI
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What are the sub encapsulations used by frame-relay?
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What Frame-relay component works as a status enquiry and reports messages?
local management interface (LMI)
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What are frame-relay LMI messages used for?
LMI messages are sent between your router and theframe-relay provider's equipment to verify and report on the status of your PVC
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What are the different statuses reported by frame-relay LMI and what are their meanings?
- Active - everything is up and operational.
- Inactive - you are connected to your frame-relayprovider, but there is a problem with the far-end connection. The problem is most likely between thefar-end router and its connection to the frame-relay provider.
- Deleted - there is a problem between your router and the frame-relay provider's equipment.
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What frame relay component is used as a keep alive signal?
LMI
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What does it mean when frame-relay no longer receives LMI messages?
it will know that there is a problem with your PVC
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What are the different types of frame-relay LMI?
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What are the different types of frame-relay mapping?
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What are the different frame-relay configuration options?
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What is the sequence of commands for configuring ppp encapsulation for frame-relay?
- Interface Serial 0/0
- Encapsulation frame-relay [ietf, cisco]
- No ip address
- Frame-relay lmi-type [cisco, ansi, q933a]
- Interface 0/0.1 point-to-point
- Ip address [ip address] [subnet mask]
- Frame-relay interface-dlci [dlci number for remote router]
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What is the sequence of commands for configuring ppp encapsulation for frame-relay?
- interface serial 0/0
- encapsulation frame-relay [ietf, cisco]
- no ip address
- frame-relay lmi-type [cisco, ansi, q933a]
- interface serial 0/0.1 multipoint
- ip address [ip address] [subnet mask]
- frame-relay interface-dlci [dlci number for remote router] broadcast (if you want to traverse your NBMA network)
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What will the command show frame-relay lmi provide you?
will show LMI statistics, including the number ofstatus enquiries sent and received. Because the status enquiries and responsesare used as continuous
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What will the command show frame-relay pvc provide you?
- the status of your PVC. The status should read ACTIVE.
- BECN and FECN messages
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What will the command show frame-relay map provide you?
- static maps configured
- maps created by inverse-arp
- the status of your PVC
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What will the command debug frame-relay lmi provide you?
LMI messages in real-time
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Which commands will show LMI statistics, including the number ofstatus enquiries sent and received?
show frame-relay lmi
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Which command will inform you to the status of your PVC? The status should read ACTIVE. This is also where you will see if your router is receiving BECN and FECN messages.
show frame-relay pvc
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Which command will show you any static maps configured and maps created by inverse-arp? This command will also show you the status of your PVC
show frame-relay map
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Which command shows you LMI messages in real-time?
debug frame-relay lmi
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Which WAN technology uses synchronous serial interfaces
Packet Switched
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Which WAN technology can use a virtual circuit to establish a connection between two or more sites and your data packets are switched across a service provider's network ? (The service provider's network istransparent to the customer; you will not be able to see any of your provider'sequipment.)
Packet Switched
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What are the traits of a packet switched network?
- broadcast traffic is not allowed to traverse frame-relay traffic. There are ways, however, to circumvent the NBMA nature of frame-relay to allow broadcasts to cross the frame-relay cloud.
- uses synchronous serial interfaces
- virtual circuit is established between two or more sites and your data packets are switched across a service provider's network (The service provider's network is transparent to the customer; you will not be able to see any of your provider's equipment.)
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What is a subinterface
a subset of an existing physical interface. As far as the router is concerned, the subinterface is a separate interface. By creating subinterfaces, each circuit can be on its own subnet.
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What are the different subinterface types?
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What does the ppp do for subinterfaces?
- maps a single IP subnet to a single subinterface and DLCI
- addresses the issue of split horizon
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What does multipoint do for subinterfaces?
maps a single IP subnet to multiple DLCIs on a subinterface
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What is the purpose of NAT?
- Translates multiple inside hosts to a single outside IP
- Solves overlapping IP space
- Assigns a cluster of servers (each with different local IP addresses) a single IP
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What are the advantages of NAT?
- Conserves the registers IP address space
- Hides the originating IP address
- A work around to have to re-address an entire network
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What does NAT stand for?
Network Address Translation
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What are the disadvantages of NAT?
- Changes the source IP address
- Makes Troubleshooting difficult
- Adds an extra delay in the transmission of data packets
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What is the term that refers (typically) to the private side of the network,usually the source of addresses that are being translated?
Inside
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Inside Local, Inside Global, Outside Local, or Outside Global? (Hosts on the network)These addresses are assigned to inside hosts and are the ones being translated. Inside Local IPs are often RFC 1918 private IPs such as 192.168.x.x, 172.16–31.x.x and 10.x.x.x
Inside Local
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Inside Local, Inside Global, Outside Local, or Outside Global? (Global interface of the router) These are the addresses to which Inside Locals get translated; often registered IPs obtained from the ISP
Inside Global
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The term for the public side of the network, the address space to which insidehosts are being translated
Outside
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Inside Local, Inside Global, Outside Local, or Outside Global? (Theinternal ip address of servers who are also available to the internet with anoutside IP address) These are the addresses of Outside Global hosts as they appear on the Inside network; they might or might not have been translated from Outside to Inside, depending on the configuration
Outside Local
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Inside Local, Inside Global, Outside Local, or Outside Global? (external web servers with an external IP address) (1) These are typically registered IPs assigned to web servers, mail servers, or any host that is reachable on the public network (Internet, usually) itself
Outside Global
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Which RFC article defines private IP addresses?
1918
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What does RFC 1918 define?
private IP addresses
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What network addresses are the private network addresses?
- 192.168.x.x
- 172.16–31.x.x
- 10.x.x.x
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What is static NAT?
- refers to the creation of a one-to-one mapping of anInside Local IP to an Inside Global IP.
- gives hosts such as mail or web servers access to the Internet even though they are physically on the private network.
- It allows us to access that web server from the Internet by creating a static NAT entry from an outside global IP to the server's inside local IP
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Does Static NAT conserve IP addresses?
no
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What is dynamic NAT?
Enables an inside host to get an outside address when needed; this saves us the trouble of creating multiple static maps, one for each host that wants to use the Internet
-
Does dynamic NAT conserve IP addresses?
no
-
What is a NAT pool?
group of addresses that are available for translation.
-
What is the best way to create an address pool?
access lists
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What is the sequence of commands used to create a dynamic NAT using address pool?
- Ip nat pool [create a pool name] [first ip] [last ip] netmask [subnet mask]
- Ip nat inside source list 1 pool [pool name created]
- Interface e0
- Ip nat inside
- Interface s0
- Ip nat outside
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What is PAT?
Port Address Translation
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What is a nick name for PAT?
extended NAT entry
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What does PAT do?
an inside host is given a translation entry that uses not only the host's IP address, but also its source port.
-
What is the sequence of commands used to enable PAT?
- Access-list 1 permit [network address] [host mask]
- Ip nat inside source list 1 interface [interface name] overload
- Interface e0
- Ip nat inside
- Interface s0
- Ip nat outside
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What commands can be used to troubleshoot NAT?
- show nat ip translations
- show nat ip statistics
- clear ip nattranslations *
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What does the command show ip nat translations provide you?
that your NAT configuration is working
-
What does the command show nat ip statistics provide you?
gives us a snapshot of how many translations have been performed, a general overview of how the NAT device is configured, and how much of our pool has been used.
-
What does the command clear ip nat translations * do you you?
clears all dynamic and extended translation entries
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Which command will show you that your NAT configuration is working
show ip nat translations
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Which command gives us a snapshot of how many translations have been performed, a general overview of how the NAT device is configured, and how much of our pool has been used?
show ip nat statistics
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Which command clears all dynamic and extended translation entries
clear ip nat translations *
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How do you clear static NAT entries?
remove the command from your running-config
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