Cisco 100-105 Free Practice Questions

Answer: A,D 

Explanation: 

The source and destination addresses are on the same network therefore, a default gateway is not necessary for communication between these two addresses. 

Answer: C 

Explanation: 

248 mask uses 5 bits (1111 1000) 

42 IP in binary is (0010 1010) 

The base subnet therefore is the lowest binary value that can be written without changing 

the output of an AND operation of the subnet mask and IP... 

1111 1000 AND 

0010 1010 equals 

0010 1000 - which is .40 

/24 is standard class C mask. 

Adding the 5 bits from the .248 mask gives /29 

Answer: B 

Explanation: 

First, notice that the more-specific routes will always be favored over less-specific routes regardless of the administrative distance set for a protocol. In this case, because we use OSPF for three networks (172.16.100.0 0.0.0.3, 172.16.100.64 0.0.0.63, 172.16.100.128 0.0.0.31) so the packets destined for these networks will not be affected by the default route. The default route configured on R1 “ip route 0.0.0.0 0.0.0.0 serial0/0 will send any packet whose destination network is not referenced in the routing table of router R1 to R2, it doesn’t drop anything. These routes are declared in R1 and the question says that “OSPF has been correctly configured on router R2, so network directly connected to router R2 can communicate with those three subnetworks. As said above, the default route configured on R1 will send any packet destined for a network that is not referenced in its routing table to R2; R2 in turn sends it to R1 because it is the only way and a routing loop will occur. 

Answer: B,D 

Explanation: 

Using a firewall is a must for networks of any size to protect the internal network from outside threats and unauthorized access. SSH traffic is encrypted while telnet is not, so it is always recommended to use SSH. 

Answer: B 

Explanation: 

This module describes how to configure Network Address Translation (NAT) for IP address conservation and how to configure inside and outside source addresses. This module also provides information about the benefits of configuring NAT for IP address conservation. NAT enables private IP internetworks that use nonregistered IP addresses to connect to the Internet. NAT operates on a device, usually connecting two networks, and translates the private (not globally unique) addresses in the internal network into legal addresses before packets are forwarded onto another network. NAT can be configured to advertise to the outside world only one address for the entire network. This ability provides additional security by effectively hiding the entire internal network behind that one address. NAT is also used at the enterprise edge to allow internal users access to the Internet and to allow Internet access to internal devices such as mail servers. 

Answer: A 

Explanation: 

Router Switching Function (1.2.1.1)A primary function of a router is to forward packets toward their destination. This is accomplished by using a switching function, which is the process used by a router to accept a packet on one interface and forward it out of another interface. A key responsibility of the switching function is to encapsulate packets in the appropriate data link frame type for the outgoing data link. NOTE In this context, the term “switching” literally means moving packets from source to destination and should not be confused with the function of a Layer 2 switch. After the router has determined the exit interface using the path determination function, the router must encapsulate the packet into the data link frame of the outgoing interface. What does a router do with a packet received from one network and destined for another network? The router performs the following three major steps: 

. Step 1. De-encapsulates the Layer 3 packet by removing the Layer 2 frame header and trailer. . Step 2. Examines the destination IP address of the IP packet to find the best path in the routing table. . Step 3. If the router finds a path to the destination, it encapsulates the Layer 3 packet into a new Layer 2 frame and forwards the frame out the exit interface. 

Answer: B,C 

Explanation: 

A single interface may be assigned multiple addresses of any type (unicast, anycast, 

multicast). 

Every IPv6-enabled interface must contain at least one loopback and one link-local 

address. 

Optionally, every interface can have multiple unique local and global addresses. 

IPv6 host addresses can be assigned in multiple ways: 

Static configuration 

Stateless autoconfiguration 

DHCPv6 

When IPv6 is used over Ethernet networks, the Ethernet MAC address can be used to 

generate the 64-bit interface ID for the host. This is called the EUI-64 address. 

Since MAC addresses use 48 bits, additional bits must be inserted to fill the 64 bits 

required. 

Reference: 

http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd 

8026003d.pdf 

Answer: A,C,E 

Explanation: 

Routing overhead is the amount of information needed to describe the changes in a dynamic network topology. All routers in an OSPF area have identical copies of the topology database and the topology database of one area is hidden from the rest of the areas to reduce routing overhead because fewer routing updates are sent and smaller routing trees are computed and maintained (allow extensive control of routing updates and confine network instability to one area of the network). 

Answer: D,F 

Explanation: 

This question is to examine the conditions for OSPF to create neighborhood. 

So as to make the two routers become neighbors, each router must be matched with the 

following items: 

1.

 The area ID and its types; 

2.

 Hello and failure time interval timer; 

3.

 OSPF Password (Optional); 

Answer: E 

Explanation: 

When frame receives the frame, it checks the source address on MAC table if MAC address found in MAC table it tries to forward if not in MAC table adds the Address on MAC table. After checking the source address, it checks the destination address on MAC table, if MAC address found on MAC table it forwards to proper ports otherwise floods on all ports except the source port. 

Answer: E 

Explanation: 

UDP provides a connectionless datagram service that offers best-effort delivery, which means that UDP does not guarantee delivery or verify sequencing for any datagrams. A source host that needs reliable communication must use either TCP or a program that provides its own sequencing and acknowledgment services. 

Answer: C 

Explanation: 

SStatic EEGP DEIGRP RRIP OOSPF 

Default Administrative distance of EIGRP protocol is 90 then answer is C 

Default Distance Value TableThis table lists the administrative distance default values of the protocols that Cisco supports: 

Route Source Default Distance Values 

Connected interface 0 Static route 1 Enhanced Interior Gateway Routing Protocol (EIGRP) summary route 5 External Border Gateway Protocol (BGP) 20 Internal EIGRP 90 IGRP 100 OSPF 110 Intermediate System-to-Intermediate System (IS-IS) 115 Routing Information Protocol (RIP) 120 Exterior Gateway Protocol (EGP) 140 On Demand Routing (ODR) 160 External EIGRP 170 Internal BGP 200 Unknown* 255 

Answer: A,C 

Explanation: 

In an inbound access list, packets are filtered as they enter an interface. Extended access lists are used to filter protocol specific packets. Access lists can be used in a variety of situations when the router needs to be given guidelines for decision-making. These situations include: Filtering traffic as it passes through the router To control access to the VTY lines (Telnet) To identify "interesting" traffic to invoke Demand Dial Routing (DDR) calls To filter and control routing updates from one router to another There are two types of access lists, standard and extended. Standard access lists are applied as close to the destination as possible (outbound), and can only base their filtering criteria on the source IP address. The number used while creating an access list specifies the type of access list created. The range used for standard access lists is 1 to 99 and 1300 to 1999. Extended access lists are applied as close to the source as possible (inbound), and can base their filtering criteria on the source or destination IP address, or on the specific protocol being used. The range used for extended access lists is 100 to 199 and 2000 to 2699. Other features of access lists include: Inbound access lists are processed before the packet is routed. Outbound access lists are processed after the packet has been routed to an exit interface. An "implicit deny" is at the bottom of every access list, which means that if a packet has not matched any preceding access list condition, it will be filtered (dropped). Access lists require at least one permit statement, or all packets will be filtered (dropped). One access list may be configured per direction for each Layer 3 protocol configured on an interface The option stating that in an inbound access list, packets are filtered before they exit an interface is incorrect. 

Packets are filtered as they exit an interface when using an outbound access list. The option stating that a deny statement must be specified at the end of each access list in order to filter unwanted traffic is incorrect. There is an implicit deny at the bottom of every access list. When a line is added to an existing access list, it is not inserted at the beginning of the access list. It is inserted at the end. This should be taken into consideration. For example, given the following access list, executing the command access-list 110 deny tcp 192.168.5.0 0.0.0.255 any eq www would have NO effect on the packets being filtered because it would be inserted at the end of the list, AFTER the line that allows all traffic. 

access-list 110 permit ip host 192.168.5.1 any access-list 110 deny icmp 192.168.5.0 0.0.0.255 any echo access-list 110 permit any any 

Answer: C 

Explanation: 

http://www.cisco.com/en/US/products/hw/switches/ps607/products_tech_note09186a00801 25913.shtml 

Each time you power up the switch, eight Power-On Self Tests (POSTs) run automatically. POSTs check the most important system components before the switch begins to forward packets. When the switch begins the POST, the port status LEDs display amber for two seconds, and then display green. As each test runs, the port status LEDs go out. 1x is the first to go out. The port status LEDs for ports 2x through 8x go out sequentially as the system completes a test. When the POST completes successfully, the port status LEDs go out. This indicates that the switch is operational. If a test fails, the port status LED associated with the test displays amber. The system LED also displays amber. Not E: From Cisco IOS Software Release 11.2(8.5) SA6 onwards, the port and system LEDs both remain amber after a POST failure. In the earlier Cisco IOS Software Releases, only the LEDs of failed linked ports remained amber. 

Answer: C 

Explanation: 

Convert bit-length prefix to quad-dotted decimal representation, then from it find the number of bits used for subnetting you can find previously calculated number of subnets by separating subnets each having value of last bit used for subnet masking Find that your IP address is in which subnet, that subnet's first address is network address and last address is broadcast address. Based on above steps the answer is option C