CCNA – Switch Questions

Question 1

Which two commands can be used to verify a trunk link configuration status on a Cisco switch? (choose two)
A. show interfaces trunk
B. show interfaces switchport
C. show ip interface brief
D. show interfaces vlan

Answer: A B

Explanation

The “show interfaces trunk” command and “show interfaces switchport” command can be used to verify the status of an interface (trunking or not). The outputs of these commands are shown below (port Ethernet 1/0 has been configured as trunk):

The “show ip interface brief” command only gives us information about the IP address, the status (up/down) of an interface:

The “show interfaces vlan” command only gives us information about that VLAN, not about which ports are the trunk links:

Question 2

Refer to the exhibit. The following commands are executed on interface fa0/1 of 2950Switch.
2950Switch(config-if)#switchport port-security
2950Switch(config-if)#switchport port-security mac-address sticky
2950Switch(config-if)#switchport port-security maximum 1
The Ethernet frame that is shown arrives on interface fa0/1. What two functions will occur when this frame is received by 2950Switch? (Choose two)

A. The MAC address table will now have an additional entry of fa0/1 FFFF.FFFF.FFFF.
B. Only host A will be allowed to transmit frames on fa0/1.
C. This frame will be discarded when it is received by 2950Switch.
D. All frames arriving on 2950Switch with a destination of 0000.00aa.aaaa will be forwarded out fa0/1.
E. Hosts B and C may forward frames out fa0/1 but frames arriving from other switches will not be forwarded out fa0/1.
F. Only frames from source 0000.00bb.bbbb, the first learned MAC address of 2950Switch, will be forwarded out fa0/1.

Answer: B D

Question 3

Which Cisco Catalyst feature automatically disables the port in an operational PortFast upon receipt of a BPDU?
A. BackboneFast
B. UplinkFast
C. Root Guard
D. BPDU Guard
E. BPDU Filter

Answer: D

Explanation

We only enable PortFast feature on access ports (ports connected to end stations). But if someone does not know he can accidentally plug that port to another switch and a loop may occur when BPDUs are being transmitted and received on these ports.
With BPDU Guard, when a PortFast receives a BPDU, it will be shut down to prevent a loop -> D is correct.

Question 4

Why will a switch never learn a broadcast address?
A. Broadcast frames are never sent to switches.
B. Broadcast addresses use an incorrect format for the switching table.
C. A broadcast address will never be the source address of a frame.
D. Broadcasts only use network layer addressing.
E. A broadcast frame is never forwarded by a switch.

Answer: C

Question 5

Which three statements accurately describe layer 2 Ethernet switches? (choose three)
A. Microsegmentation decreases the number of collisions on the network.
B. If a switch receives a frame for an unknown destination.it uses ARP to resolve the address.
C. Spanning Tree Protocol allows switches to automatically share vlan information.
D. In a property functioning network with redundant switched paths, each switched segment will contain one root bridge with all its ports in the forwarding state. All other switches in that broadcast domain will have only one root port.
E. Establishing vlans increases the number of broadcast domains.
F. Switches that are configured with vlans make forwarding decisions based on both layer 2 and layer 3 address information.

Answer: A D E

Question 6

Switch ports operating in which two roles will forward traffic according to the IEEE 802.1w standard? (Choose two)
A. alternate
B. backup
C. designated
D. disabled
E. root

Answer: C E

Explanation

IEEE 802.1w is the standard of Rapid Spanning Tree Protocol (RSTP). There are 5 port roles in this standard: Root port, Designated port, Alternative port, Backup port and Disabled port. In these 5 port roles, only Root port and Designated port can forward traffic.

Question 7

Select the action that results from executing these commands:
Switch(config-if)# switchport port-security
Switch(config-if)# switchport port-security mac-address sticky
A. A dynamically learned MAC address is saved in the startup-configuration file.
B. A dynamically learned MAC address is saved in the running-configuration file.
C. A dynamically learned MAC address is saved in the VLAN database.
D. Statically configured MAC addresses are saved in the startup-configuration file if frames from that address are received.
E. Statically configured MAC addresses are saved in the running-configuration file if frames from that address are received.

Answer: B

Explanation

The full syntax of the second command is:
switchport port-security mac-address sticky [MAC]
If we don’t specify the MAC address (like in this question) then the switch will dynamically learn the attached MAC Address and place it into your running-configuration -> B is correct.

Question 8

What is valid reason for a switch to deny port access to new devices when port security is enabled?
A. The denied MAC addresses have already been learned or configured on another secure interface in the same VLAN.
B. The denied MAC address are statically configured on the port.
C. The minimum MAC threshold has been reached.
D. The absolute aging times for the denied MAC addresses have expired.

Answer: A

Explanation

A security violation occurs in either of these situations:
* When the maximum number of secure MAC addresses is reached on a secure port and the source MAC address of the ingress traffic is different from any of the identified secure MAC addresses, port security applies the configured violation mode.
* If traffic with a secure MAC address that is configured or learned on one secure port attempts to access another secure port in the same VLAN, applies the configured violation mode.
From the second statement we can figure out A is the correct answer. But for your information we will discuss other answers as well.
Answer B is not correct because we can’t configured which MAC address will be denied. We can only configure which MAC is allowed.
We can only configure the maximum MAC threshold, not the minimum threshold -> C is not correct.
The aging times are only configured for allowed MAC addresses, not for denied MAC -> D is correct.
For your information about aging time:
When the aging type is configured with the absolute keyword, all the dynamically learned secure addresses age out when the aging time expires
This is how to configure the secure MAC address aging type on the port:
Router(config-if)# switchport port-security aging type absolute
and configure the aging time (aging time = 120 minutes)
Router(config-if)# switchport port-security aging time 120
When this command is used, all the dynamically learned secure addresses age out when the aging time expires

Question 9

A network administrator needs to configure port security on a switch. Which two statements are true? (Choose two)
A. The network administrator can apply port security to dynamic access ports
B. The network administrator can configure static secure or sticky secure mac addresses in the voice vlan.
C. The sticky learning feature allows the addition of dynamically learned addresses to the running configuration.
D. The network administrator can apply port security to EtherChannels.
E. When dynamic mac address learning is enabled on an interface, the switch can learn new addresses up to the maximum defined.

Answer: C E

Question 10

Refer to the exhibit. Which statement is true?

A. The Fa0/11 role confirms that SwitchA is the root bridge for VLAN 20.
B. VLAN 20 is running the Per VLAN Spanning Tree Protocol.
C. The MAC address of the root bridge is 0017.596d.1580.
D. SwitchA is not the root bridge, because not all of the interface roles are designated.

Answer: D

Explanation

Only non-root bridge can have root port. Fa0/11 is the root port so we can confirm this switch is not the root bridge -> A is not correct.
From the output we learn this switch is running Rapid STP, not PVST -> B is not correct.
0017.596d.1580 is the MAC address of this switch, not of the root bridge. The MAC address of the root bridge is 0017.596d.2a00 -> C is not correct.
All of the interface roles of the root bridge are designated. SwitchA has one Root port and 1 Alternative port so it is not the root bridge -> D is correct.

Question 11

A technician has installed SwithchB and needs to configure it for remote access from the management workstation connected SwitchA. Which set of commands is required to accomplish this task?
A.
SwitchB(config)#interface FastEthernet 0/1
SwitchB(config)#ip address 192.168.8.252 255.255.255.0
SwitchB(config)#no shutdown
B.
SwitchB(config)#ip default-gateway 192.168.8.254
SwitchB(config)#interface vlan 1
SwitchB(config)#ip address 192.168.8.252 255.255.255.0
SwitchB(config)#no shutdown
C.
SwitchB(config)#interface vlan 1
SwitchB(config)#ip address 192.168.8.252 255.255.255.0
SwitchB(config)#ip default-gateway 192.168.8.254 255.255.255.0
SwitchB(config)#no shutdown
D.
SwitchB(config)#ip default-network 192.168.8.254
SwitchB(config)#interface vlan 1
SwitchB(config)#ip address 192.168.8.252 255.255.255.0
SwitchB(config)#no shutdown

Answer: B

Explanation

To remote access to SwitchB, it must have a management IP address on a VLAN on that switch. Traditionally, we often use VLAN 1 as the management VLAN (but in fact it is not secure).
In the exhibit, we can recognize that the Management Workstation is in a different subnet from the SwitchB. For intersubnetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.

Question 12

A network administrator wants to ensure that only the server can connect to port Fa0/1 on a Catalyst switch. The server is plugged into the switch Fa0/1 port and the network administrator is about to bring the server online. What can the administrator do to ensure that only the MAC address of the server is allowed by switch port Fa0/1? (Choose two)
A. Configure port Fa0/1 to accept connections only from the static IP address of the server.
B. Employ a proprietary connector type on Fa0/1 that is incompatible with other host connectors.
C. Configure the MAC address of the server as a static entry associated with port Fa0/1.
D. Bind the IP address of the sewer to its MAC address on the switch to prevent other hosts from spoofing the server IP address.
E. Configure port security on Fa0/1 to reject traffic with a source MAC address other than that of the server.
F. Configure an access list on the switch to deny server traffic from entering any port other than Fa0/1.

Answer: C E

Explanation

We can”configure the MAC address of the server as a static entry associated with port Fa0/1″ with this command:
Switch(config-if)#switchport port-security mac-address sticky 0000.00AA.AAAA.AAAA
and “configure port security on Fa0/1 to reject traffic with a source MAC address other than that of the server” with these commands:
Switch(config-if)#switchport port-security maximum 1 (only allow 1 MAC address and that is the static MAC address)
Also we often define what will the switch do if the security is violated:
Switch(config-if)#switchport port-security violation shutdown

Question 13

The network security policy requires that only one host be permitted to attach dynamically to each switch interface. If that policy is violated, the interface should shut down. Which two commands must the network administrator configure on the 2950 Catalyst switch to meet this policy? (Choose two)
A. Switch1(config-if)#switchport port-security maximum 1
B. Switch1(config)#mac-address-table secure
C. Switch1(config)#access-list 10 permit ip host
D. Switch1(config-if)#switchport port-security violation shutdown
E. Switch1(config-if)#ip access-group 10

Answer: A D

CCNA – Drag and Drop 5

Question 1

Drag the Cisco default administrative distance to the appropriate routing protocol or route (Not all options are used)

Answer:

+ RIP: 120
+ OSPF: 110
+ static route referencing IP address of next hop: 1
+ internal EIGRP route: 90
+ directly connected network: 0

Question 2

Drag the term on the left to its definition on the right (not all options are used)

Answer:

+ poison reverse: A router learns from its neighbor that a route is down and the router sends an update back to the neighbor with an infinite metric to that route
+ LSA: The packets flooded when a topology change occurs, causing network routers to update their topological databases and recalculate routes
+ split horizon: This prevents sending information about a routeback out the same interface that originally learned about the route
+ holddown timer: For a given period, this causes the router to ignore any updates with poorer metrics to a lost network

Question 3

Drag the description on the left to the correct router mode on the right

Answer:

+ user EXEC mode: limited to basic monitoring commands
+ privileged EXEC mode: provide access to all other router commands
+ global configuration mode: commands that affect the entire system
+ specific configuration mode: commands that affect interfaces/processes only
+ setup mode: interactive configuration dialog

Question 4

Drag each definition on the left to the matching term on the right

Answer:

+ cost: a configurable value based by default on the bandwidth of the interface
+ load: the amount of activity on a network resource
+ bandwidth: the data capacity of a link
+ hop count: the number of point-to-point links in a transmission path
+ reliability: usually refers to the bit error rate of each network link
+ delay: the amount of time required to move a packet from source to destination

CCNA – Drag and Drop 4

Question 1

Drag the function on the left to the matching security appliance or application on the right. (Not all functions are used)

Answer:

1) antispyware: detects software designed to capture sensitive information and removes it from the computer
2) antivirus: prevents known malicious programs from being installed on workstations
3) IDS: identifies malicious network traffic and alerts network personnel
4) firewall: filters traffic based on source and destination IP address or traffic type

Question 2

Drag the Frame Relay acronym on the left to match its definition on the right. (Not all acronyms are used)

Answer:

1) a router is this type of device: DTE
2) the most common type of virtual circuit: PVC
3) provides status messages between DTE and DCE devices: LMI
4) identifies the virtual connection between the DTE and the switch: DLCI

Question 3

The left describes some types of connections while the right describes some types of cables. Drag the items on the left to the proper locations.

Answer:

Explanation:

To specify when we use crossover cable or straight-through cable, we should remember:
Group 1: Router, Host(PC), Server
Group 2: Hub, Switch
One device in group 1 + One device in group 2: use straight-through cable
Two devices in the same group: use crossover cable
For example: we use straight-through cable to connect switch to router, switch to host, hub to host, hub to server… and we use crossover cable to connect switch to switch, switch to hub, router to router, host to host… ).
+ We can connect a modem to router auxiliary port using a rollover cable. Recall that the purpose of the router’s auxiliary port is for connecting to a modem and most Cisco routers have a second port on the back called the auxiliary port. We can use this port in case of a far-away router goes down, the administrator can have someone in the area go to the router, plug in a modem and access to the router remotely (if using the console port, we have to go to the site to work with that router).
+ We can connect a PC serial port to a switch/router console port through the RJ-45 to DB-9 or RJ-45 to DB-25 adapter (at the PC end), depending on the computer.

Question 4

The above provides some descriptions, while the below provides some routing protocols. Drag the above items to the proper locations.

Answer:

Explanation:

Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary routing protocol, so it is vendor-specific. By default, EIGRP internal routes have an administrative distance value of 90.
OSPF uses cost as its metric. By default, the cost of an interface is calculated based on bandwidth with the formula cost= 10000 0000/bandwith (in bps). OSPF elects a DR on each broadcast and nonbroadcast multiaccess networks (like Ethernet and Frame Relay environments, respectively). It doesn’t elect a DR on point-to-point link (like a serial WAN).

Question 5

As a CCNA candidate, you are required to have a firm understanding of the OSI model. At which layers of the OSI model do Wide Area Networks operate in? Please drag the items to the proper locations.

Answer:

Explanation

WAN operates in the two lowest layers which are Data Link and Physical layers.

CCNA – Drag and Drop 3

Question 1

Drag the security features on the left to the specific security risks they help protect against on the right. (Not all options are used)

Answer:

1) VTY password: remote access to device console
2) console password: access to the console 0 line
3) access-group: access to connected networks or resources
4) service password-encryption: viewing of passwords
5) enable secret: access to privileged mode
The unselected left-box – CHAP – is used to verify the identity of the peer by means of a three-way handshake.

Question 2

Refer to the exhibit. PC-A is sending packets to the FTP server. Consider the packets as they leave RA interface Fa0/0 forwards RB. Drag the correct frame and packet address to their places in the table.

Answer:

Source MAC: 0000.0C93.9999
Destination MAC: 0000.0C89.3333
Source IP: 172.16.21.7
Destination IP: 172.16.34.250

Explanation

Remember these rules:
The IP addresses (of source and destination) of a packet never change during the transportation through the network. For example if PC-A wants to send a packet to PC-Z then the source and destination IP addresses of the packet will be the IP addresses of PC-A and PC-Z no matter how many devices they go through.
The MAC addresses, conversely, will change while passing the devices. The source MAC address is the address of the last sender and the destination MAC address is the address of the next device.

Question 3

As a network administrator, you are required to configure the network security policy. And the policy requires that only one host be permitted to attach dynamically to each switch interface. If that policy is violated, the interface should shut down. Which two commands must the network administrator configure on the 2950 Catalyst switch to meet this policy? Please choose appropriate commands and drag the items to the proper locations.

Answer:

Appropriate commands:
SW(config-if)# switchport port-security maximum 1
SW(config-if)# switchport port-security violation shutdown

Question 4

The left describes boot sequence, while the right describes the orders. Drag the items on the left to the proper locations.

Answer:

1) Step 1: The power on self test executes.
2) Step 2: The bootstrap loader in ROM executes.
3) Step 3: The IOS is located and loaded based on boot system commands in NVRAM.
4) Step 4: The configuration file is loaded from NVRAM.
5) Step 5: If no configuration file is located, the setup dialog initiates.

Explanation

When a router boots up, it performs a series of steps, called the boot sequence, to test the hardware and load the necessary software. The boot sequence consists of the following steps:
1) Power on self test (POST): tests the hardware to verify that all components of the device are operational and present.
2) The bootstrap loader in ROM executes: The bootstrap loader is a program in ROM that is used to find where a valid Cisco IOS image is located.
3) If a valid Cisco IOS image is located, it is loaded.
4) IOS loads configuration file. Once the IOS image is loaded, it will search for a valid startup configuration in NVRAM.
5) If a valid startup configuration file cannot be found, the router will load the System Configuration Dialog (sometimes called setup mode). This mode allows you to perform the initial configuration of the router.

Question 5

Drag and Drop question. Drag the items to the proper locations.
Routing has been configured on the local router with these commands:
Local(config)# ip route 0.0.0.0 0.0.0.0 192.168.1.1
Local(config)# ip route 10.1.0.0 255.255.255.0 192.168.2.2
Local(config)# ip route 10.1.0.0 255.255.0.0 192.168.3.3
Drag each destination IP address on the top to its correct next hop address at the bottom.

Answer:

Next hop 192.168.1.1:
+ 10.2.1.3
+ 10.6.8.4
Next hop 192.168.2.2:
+ 10.1.0.14
+ 10.1.0.123
Next hop 192.168.3.3:
+ 10.1.1.10
+ 10.1.4.6

Explanation

If we have many entries matching for next hop ip address then the router will choose the one with most specific path to send the packet. This is called the “longest match” rule, the route with the most bits in the mask set to “1″ will be chosen to route packet.

Question 6

If a Cisco router has learned about network 10.1.1.0 from multiple sources, the router will select and install only one entry into the routing table. Indicate the order of preference that the router will use by dragging the routes on the left to the order of preference category on the right.

Answer:

1) First preference: S 10.1.1.0 is directly connected, Serial1
2) Second preference: S 10.1 1.0/24 [1/0] via 10.1.2.2
3) Third preference: D 10.1.1.0/24 [90/2172416] via 10.1.5.5, Serial0
4) Fourth preference: O 10.1.1.0/24 [ 110/789] via 10.1.3.1, Serial0
5) Fifth preference: R 10.1.1.0/24 [120/3] via 10.1.3.1, Senal0

Explanation

Administrative distance is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. It is a measure of the trustworthiness of the source of the routing information. The smaller the administrative distance value, the more reliable the protocol.
In this question, notice that the destination of all routes is 10.1.1.0/24 so we need to use Administrative distance of each routing protocol to specify the priority of each route. Below lists the Administrative Distance default values of popular routing protocols:
+ Directly connected: 0
+ Static route: 1
+ EIGRP (symbolize by “D”): 90
+ OSPF (symbolize by “O”): 110
+ RIP (symbolize by “R”): 120

CCNA – Drag and Drop 2

Question 1

The left describes OSI layers, while the right provides some terms. Drag the items on the right to the proper locations.

Answer:

Network Layer:
1) IP addresses
2) packets
3) routing
Transport Layer:
1) windowing
2) UDP
3) segments

Question 2

The above describes some categories, while the below provides their corresponding router output lines. Drag the above items to the proper locations.

Answer:

1) Port operational: Serial0/1 is up, line protocol is up
2) Layer 2 problem: Serial0/1 is up, line protocol is down
3) Layer 1 problem: Serial0/1 is down, line protocol is down
4) Port disabled: Serial0/1 is administrator down, line protocol is down

Explanation:

A simple way to find out which layer is having problem is to remember this rule: “the first statement is for Layer 1, the last statement is for Layer 2 and if Layer 1 is down then surely Layer 2 will be down too”, so you have to check Layer 1 before checking Layer 2. For example, from the output “Serial0/1 is up, line protocol is down” we know that it is a layer 2 problem because the first statement (Serial0/1 is up) is good while the last statement (line protocol is down) is bad. For the statement “Serial0/1 is down, line protocol is down”, both layers are down so the problem belongs to Layer 1.
There is only one special case with the statement “…. is administrator down, line protocol is down”. In this case, we know that the port is currently disabled and shut down by the administrators.

Question 3

A user is unable to connect to the Internet. Based on the layered approach to troubleshooting and beginning with the lowest layer. Follow the guide and drag the contents to relevant modules.

Answer:

1) Verify Ethernet cable connection: Step 1
2) Verify NIC operation: Step 2
3) Verify IP configuration: Step 3
4) Verify URL: Step 4

Explanation:

The question asks us to “begin with the lowest layer” so we have to begin with Layer 1: verify physical connection; in this case an Ethernet cable connection. For your information, “verify Ethernet cable connection” means that we check if the type of connection (crossover, straight-through, rollover…) is correct, the RJ45 headers are plugged in, the signal on the cable is acceptable…
Next we “verify NIC operation”. We do this by simply making a ping to the loopback interface 127.0.0.1. If it works then the NIC card (layer 1,2) and TCP/IP stack (layer 3) are working properly.
Verify IP configuration belongs to layer 3. For example, checking if the IP can be assignable for host, the PC’s IP is in the same network with the gateway…
Verifying the URL by typing in your browser some popular websites like google.com, microsoft.com to assure that the far end server is not down (it sometimes make we think we can’t access to the Internet). We are using a URL so this step belongs to layer 7 of the OSI model.

Question 4

The left describes the types of cables, while the right describes the purposes of the cables. Drag the items on the left to the proper locations. (Not all items can be used).

Answer:

1) straight-through: switch access port to router
2) crossover: switch to switch
3) rollover: PC COM port to switch

Explanation:

To remember which type of cable you should use, follow these tips:
- To connect two serial interfaces of 2 routers we use serial cable
– To specify when we use crossover cable or straight-through cable, we should remember:
Group 1: Router, Host, Server
Group 2: Hub, Switch
One device in group 1 + One device in group 2: use straight-through cable
Two devices in the same group: use crossover cable
For example: we use straight-through cable to connect switch to router, switch to host, hub to host, hub to server… and we use crossover cable to connect switch to switch, switch to hub, router to router, host to host… )

Question 5

The left describes the types of switch ports, while the right describes the features. Drag the options on the right to the proper locations.

Answer:

Access Port:
- Carries traffic for a single VLAN
– Uses a straight-through cable to connect a device
– Connects an end-user workstation to a switch
Trunk Port:
- Carries traffic for a multiple VLAN
– Uses 802.1q to identify traffic from different VLANs
– Facilitates interVLAN communications when connected to a Layer 3 device

Question 6

The above describes the Spanning-Tree Protocol port states, while the below describes their functions. Drag the above items to the proper locations.

Answer:

- Learning: populating the MAC address table but not forwarding data frames
– Forwarding: sending and receiving data frames
– Listening: preparing to forward data frames without populating the MAC address table
– Blocking: preventing the use of looped paths

CCNA – Drag and Drop

Question 1:

A dental firm is redesigning the network that connects its three locations. The administrator gave the networking team 192.168.164.0 to use for addressing the entire netwok. After subnetting the address, the team is ready to assign the addresses. The administrator plans to configure ip subnet-zero and use RIP v2 as the routing protocol. As a member of the networking team, you must address the network and at the same time conserver unused addresses for future growth. With those goals in mind, drag the host addresses on the left to the correct router interface. Once of the routers is partially configured. Move your mouse over a router to view its configuration. Not all of the host addresses on the left are necessary.

Answer:

Explanation:

In short, we should start calculating from the biggest network (with 16 hosts) to the smallest one using the formula 2ⁿ – 2 (n is the number of bits we need to borrow).Therefore:
16 hosts < 2⁵ – 2 (we need to borrow 5 bits -> /27)
11 hosts < 2⁴ – 2 (borrow 4 bits -> /28)
5 hosts < 2³ – 2 (borrow 3 bits -> /29)
From the available ip addresses, we see that each of them has only one suitable solution (they are 192.168.164.149/27,192.168.164.166/28 and 192.168.164.178/29)
The smallest network is the Floss S0/0 which only requires 2 hosts = 2² – 2 (need to borrow 2 bits ->/30). There are 2 suitable answers: 192.168.164.189/30 and 192.168.164.188/30 but notice that 192.168.164.188/30 is the network address so we can not use it (because 188 = 4 * 47) -> we have to choose 192.168.164.189 as the correct solution.
In fact, it is not the formal way to solve a VLSM question so I recommend you to review your CCNA book if you haven’t grasped it well yet.

Question 2:

In order to complete a basic switch configuration, drag each switch IOS command on the left to its purpose on the right

Answer:

1) enable
2) configure terminal
3) hostname
4) Interface vlan 1
5) no shutdown
6) ip address
7) ip default-gateway

Question 3:

The Missouri branch office router is connected through its s0 interface to the Alabama Headquarters router s1 interface. The Alabama router has two LANs. Missouri users obtain Internet access through the Headquarters router. The network interfaces in the topology are addressed as follows: Missouri: e0 – 192.168.35.17/28; s0 – 192.168.35.33/28; Alabama: e0 – 192.168.35.49/28; e1 – 192.168.35.65/28; s1 – 192.168.35.34/28. The accounting server has the address of 192.168.35.66/28. Match the access list conditions on the left with the goals on the right. (Not all options on the left are used.)

Answer:

1) deny ip 192.168.35.16 0.0.0.15 host 192.168.35.66
2) deny ip 192.168.35.55 0.0.0.0 host 192.168.35.66
3) permit ip 192.168.35.0 0.0.0.255 host 192.168.35.66

Explanation:

1) The wildcard mask of the command “deny ip 192.168.35.16 0.0.0.15 host 192.16.35.66″ is 0.0.0.15, which is equal to network mask of 255.255.255.240 = /28. So the access list will deny all traffic from network 192.168.35.16/28 from accessing host 192.16.35.66, which is the IP address of accounting server.
2) The command “deny ip 192.168.35.55 0.0.0.0 host 192.168.35.66″ will deny host 192.168.35.55, which is a user and belongs to interface e0 of Alabama router (192.168.35.49/28) from accessing accounting server.
3) Because there is an implicit “deny all” command at the end of each access list so the command “permit ip 192.168.35.0 0.0.0.255 host 192.168.35.66″ will only let network 192.168.35.0/24 access accounting server whilst prevent traffic from other networks.

Question 4:

A host with the address of 192.168.125.34/27 needs to be denied access to all hosts outside its own subnet. To accomplish this, complete the command in brackets, [access-list 100 deny protocol address mask any], by dragging the appropriate options on the left to their correct placeholders on the right.

Answer:

1) ip
2) 192.168.125.34
3) 0.0.0.0
Full command: access-list 100 deny ip 192.168.125.34 0.0.0.0

Question 5:

Drag and drop the network user application to the appropriate description of its primary use (not all options are used)

Answer:

1) web browser
2) instant message
3) e-mail
4) database
5) collaboration

Question 6:

This topology contains 3 routers and 1 switch. Complete the topology.

Drag the appropriate device icons to the labeled Device Drag the appropriate connections to the locations labeled Connections. Drag the appropriate IP addresses to the locations labeled IP address

(Hint: use the given host addresses and Main router information)
To remove a device or connection, drag it away from the topology.
Use information gathered from the Main router to complete the configuration of any additional routers. No passwords are required to access the Main router . The config terminal command has been disabled for the HQ router. The router does not require any configuration.
Configure each additional router with the following

Configure the interfaces with the correct IP address and enable the interfaces. Set the password to allow console access to consolepw Set the password to allow telnet access to telnetpw Set the password to allow privilege mode access to privpw

Note: Because routes are not being added to the configurations, you will not be able to ping through the internetwork.
All devices have cable autosensing capabilities disabled.
All hosts are PC’s

Answer:

CCNA – NAT and PAT Questions

Question 1

Refer to the exhibit. What does the (*) represent in the output?

02:16:29: NAT: s=10.10.0.2->1.2.4.2, d=1.2.4.1 [51607] 02:16:29: NAT: s=1.2.4.1, d=1.2.4.2->10.10.0.2 [55227] 62:16:29: NAT*: s=10.10.0.2->1.2.4.2, d=1.2.4.1 [51608] 02:16:29: NAT*: s=10.10.0.2->1.2.4.2, d=1.2.4.1 [51609]

A. Packet is destined for a local interface to the router.
B. Packet was translated, but no response was received from the distant device.
C. Packet was not translated, because no additional ports are available.
D. Packet was translated and fast switched to the destination.

Answer: D

Explanation

The above output is from the “debug ip nat” command. In this output, the first two lines show the Domain Name System (DNS) request and reply debugging output.
In the first line (DNS request):
s=10.10.0.2->1.2.4.2: source of the IP address (10.10.0.2) and how it is being translated (to 1.2.4.2)
d=1.2.4.1: destination address of the packet
[51607]: the IP identification number of the packet
In the second line (DNS reply):
s=1.2.4.1: source of the reply
d=1.2.4.2->10.10.0.2: how the destination is being translated
The remaining lines show debugging output from a Telnet connection from a host on the inside of the network to a host on the outside of the network. All Telnet packets, except for the first packet, were translated in the fast path, as indicated by the asterisk (*).
Note: If the connection is already established, the security appliance does not need to re-check packets and the packets are sent to the Fast Path.

Question 2

Refer to the exhibit. What command sequence will enable PAT from the inside to outside network?

ip nat pool isp-net 1.2.4.10 1.2.4.240 netmask 255.255.255.0 ! interface ethernet 1 description ISP Connection ip address 1.2.4.2 255.255.255.0 ip nat outside ! interface ethernet 0 description Ethernet to Firewall eth0 ip address 10.10.0.1 255.255.255.0 ip nat inside ! access-list 1 permit 10.0.0.0 0.255.255.255

A. (config)# ip nat pool isp-net 1.2.4.2 netmask 255.255.255.0 overload
B. (config-if)# ip nat outside overload
C. (config)# ip nat inside source list 1 interface ethernet1 overload
D. (config-if)# ip nat inside overload

Answer: C

Explanation

The command “ip nat inside source list 1 interface ethernet1 overload” means:
 “ip nat”: use NAT
  “inside”: NAT from inside to outside
  “source list 1″: the source addresses can be found in access list 1
  “interface ethernet1″: NAT out of this interface
  “overload”: use NAT overload (PAT)

Question 3

Refer to the exhibit. A junior network engineer has prepared the exhibited configuration file. What two statements are true of the planned configuration for interface fa0/1? (Choose two)

A. The two FastEthernet interfaces will require NAT configured on two outside serial interfaces.
B. Address translation on fa0/1 is not required for DMZ Devices to access the Internet.
C. The fa0/1 IP address overlaps with the space used by s0/0.
D. The fa0/1 IP address is invalid for the IP subnet on which it resides.
E. Internet hosts may not initiate connections to DMZ Devices through the configuration that is shown.

Answer: B E

Explanation

Both inside FastEthernet interfaces can use only one outside interface to go to the Internet -> A is not correct.
DMZ devices use IP addresses in the range of 128.107.1.128/25 which are public IP addresses so they don’t need address translation to access the Internet -> B is correct.
The fa0/1 interface’s IP address is 128.107.1.254 255.255.255.128 (range from 128.107.1.128 to 128.107.1.255) while the IP address of s0/0 is 128.107.1.1 255.255.255.252 (ranges from 128.107.1.0 to 128.107.1.4) so they are not overlapped with each other -> C is not correct.
DMZ devices are in the range of 128.107.1.128/25 (from 128.107.1.128 to 128.107.1.255) and fa0/1 IP address (128.107.1.254) is a valid IP address on this subnet -> D is not correct.
DMZ devices (and other internal hosts) are using dynamic PAT, which is a type of dynamic NAT. With dynamic NAT, translations do not exist in the NAT table until the router receives traffic that requires translation. In other words, if DMZ devices communicate with outside hosts first, dynamic translation works fine. But if outside hosts communicate with DMZ devices first, no translation is created in NAT table and the packets will be dropped. This is the reason why “Internet hosts may not initiate connections to DMZ Devices through the configuration that is shown” -> E is correct.

Question 4

Refer to the exhibit. What statement is true of the configuration for this network?

A. The configuration that is shown provides inadequate outside address space for translation of the number of inside addresses that are supported.
B. Because of the addressing on interface FastEthernet0/1, the Serial0/0 interface address will not support the NAT configuration as shown.
C. The number 1 referred to in the ip nat inside source command references access-list number 1.
D. ExternalRouter must be configured with static routers to network 172.16.2.0/24

Answer: C

Explanation

The “list 1″ refers to the access-list number 1.

Question 5

What are two benefits of using NAT? (choose two)
A. NAT protects network security because private networks are not advertised.
B. NAT accelerates the routing process because no modifications are made on the packets.
C. Dynamic NAT facilitates connections from the outside of the network.
D. NAT facilitates end-to-end communication when IPsec is enable.
E. NAT eliminates the need to re-address all host that require external access.
F. NAT conserves addresses through host MAC-level multiplexing.

Answer: A E

Explanation

By not reveal the internal Ip addresses, NAT adds some security to the inside network -> A is correct.
NAT has to modify the source IP addresses in the packets -> B is not correct.
Connection from the outside of the network through a “NAT” network is more difficult than a more network because IP addresses of inside hosts are hidden -> C is not correct.
In order for IPsec to work with NAT we need to allow additional protocols, including Internet Key Exchange (IKE), Encapsulating Security Payload (ESP) and Authentication Header (AH) -> more complex -> D is not correct.
By allocating specific public IP addresses to inside hosts, NAT eliminates the need to re-address the inside hosts -> E is correct.
NAT does conserve addresses but not through host MAC-level multiplexing. It conserves addresses by allowing many private IP addresses to use the same public IP address to go to the Internet -> F is not correct.

Question 6

Which two statements about static NAT translations are true? (choose two)
A. They are always present in the NAT table.
B. They allow connection to be initiated from the outside.
C. They can be configured with access lists, to allow two or more connections to be initiated from the outside.
D. They require no inside or outside interface markings because addresses are statically defined.

Answer: A B

Explanation

With static NAT, translations exist in the NAT translation table as soon as you configure static NAT command(s), and they remain in the translation table until you delete the static NAT command(s).
With dynamic NAT, translations do not exist in the NAT table until the router receives traffic that requires translation. Dynamic translations have a timeout period after which they are purged from the translation table.
-> A is correct.
Because static NAT translations are always present in the NAT table so outside hosts can initiate the connection without being dropped -> B is correct.
Static translations can not be configured with access lists. To configure static NAT, we only need to specify source IP, NAT IP, inside interface & outside interface.
-> C is not correct.
We have to specify which is the inside and outside interface -> D is not correct.
For your information, below is an example of configuring static NAT:
R0(config)#int f0/0
R0(config-if)#ip nat inside
R0(config-if)#int f0/1
R0(config-if)#ip nat outside
R0(config)#ip nat inside source static 10.0.0.1 200.0.0.2

Question 7

Refer to the exhibit. Which statement about packet addresses are true during data exchange when host A makes Web-request to WWW Server, considering that there is NAT overload scheme for data passing from Corp LAN hosts to outside networks in use?

A. Source 234.15.27.226:3015 and destination 234.15.27.225:80
B. Source 200.15.239.128:3015 and destination 192.168.10.34:80
C. Destination 192.168.10.11:3015 and source 200.15.239.128:80
D. Source 192.168.10.34:80 and destination 192.168.10.254:3015
E. Destination 234.15.27.225:3015 and source 200.15.239.128:80

Answer: E

Explanation

From A to Corp router:
+ Source: 192.168.10.34: 3015 & Destination: 200.15.239.128:80
From Corp to WWW Server:
+ Source: 234.15.27.225:3015 & Destination: 200.15.239.128:80
From WWW Server to Corp:
+ Source: 200.15.239.128:80 & Destination: 234.15.27.225:3015
From Corp to Host A:
+ Source: 192.168.10.254:80 & Destination: 192.168.10.34:3015
So the only correct answer is E (from WWW server to Corp)