Updated Jan 09, 2023 Verified Pass 100-101 Exam in First Attempt Guaranteed [Q25-Q40]

Network address translation or NAT requires the Internet to be considered as an outside interface else it won’t serve the purpose it intends to.

This is a /29 address, so there are 6 usable IP’s on this subnet.

Explanation A loopback interface never comes down even if the link is broken so it provides stability for the OSPF process (for example we use that loopback interface as the router-id) The router-ID is chosen in the order below:
+ The highest IP address assigned to a loopback (logical) interface.+ If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen. -> The loopback interface will be chosen as the router ID of RouterB

In the router ospf command, the ranges from 1 to 65535 so o is an invalid number -> but To configure OSPF, we need a wildcard in the “network” statement, not a subnet mask. We also need to assgin an area to this process -> .

Explanation/Reference:
The subnet mast of the TFTP server needs to be in tune with the other network
requirements else it won’t be possible.

Explanation/Reference: 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
Topic 6, Network Device Security

Explanation/Reference: https://learningnetwork.cisco.com/thread/12389
I think the indication here is “Serial 0 is up, line protocol is down”. What causes this indication? Correct me if I am wrong. When you have this indication, a cable unplugged is not a correct answer. If you check the output of your “show interface serial 0” command again, you should notice it as “Serial 0 is down, line protocol is down. Under the “show ip int brief” you should see status = down and protocol = down as opposed to up, down. Because you disconnected the cable, layer 1 will go down, which is indicated by the serial 0 down status. The line protocol status is for layer 2. So, a cable unplugged is not a correct answer to “Serial 0 is up, line protocol is down”. Hope this helps.

Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium. CSMA/CD was created to overcome the problem of those collisions that occur when packets are transmitted simultaneously from different nodes. And trust me, good collision management is crucial, because when a node transmits in a CSMA/CD network, all the other nodes on the network receive and examine that transmission. Only bridges and routers can effectively prevent a transmission from propagating throughout the entire network! So, how does the CSMA/CD protocol work? Like this: when a host wants to transmit over the network, it first checks for the presence of a digital signal on the wire. If all is clear (no other host is transmitting), the host will then proceed with its transmission. But it doesn’t stop there. The transmitting host constantly monitors the wire to make sure no other hosts begin transmitting. If the host detects another signal on the wire, it sends out an extended jam signal that causes all nodes on the segment to stop sending data (think, busy signal). The nodes respond to that jam signal by waiting a while before attempting to transmit again. Backoff algorithms determine when the colliding stations can retransmit. If collisions keep occurring after 15 tries, the nodes attempting to transmit will then time out.

255.255.224 equal /19 in CIDR format hence the answer

When the DHCP client sends the DHCP request packet, it doesn’t have an IP address. So it uses the all-zeroes address, 0.0.0.0, as the IP source address. And it doesn’t know how to reach the DHCP server, so it uses a general broadcast address, 255.255.255.255, for the destination. So the router must replace the source address with its own IP address, for the interface that received the request. And it replaces the destination address with the address specified in the ip helper-address command. The client device’s MAC address is included in the payload of the original DHCP request packet, so the router doesn’t need to do anything to ensure that the server receives this information.
Topic 6, Network Device Security

Switches use a separate collision domain for each port, so device A must be a switch. Hubs, however, place all ports in the same collision domain so device B is a hub. Switches reside in layer 2 while hubs are layer 1 devices.