Networking Fundamentals

JN0-106 · 36 questions

• A subscriber's video-streaming complaint reaches a rural cooperative's NOC, and the on-call tech traces the traffic path from the head-end's web application down through the TCP/IP stack toward the physical fiber uplink. As the data moves down through each layer of the stack, what happens to it?
• A field technician wiring a new subscriber aggregation switch at a rural cooperative's point of presence needs to know which layer of the OSI model is responsible for physical addressing and for delivering frames between devices on the same local segment. Which layer is that?
• At a small rural head-end, a cooperative still connects four legacy DSLAMs to a single unmanaged hub before uplinking to the core switch. Two DSLAMs transmit at the same instant and their electrical signals collide on the shared hub segment. Which term describes the set of ports where a collision like this can occur?
• A cooperative's network engineer segments subscribers in a small town into two VLANs on the same aggregation switch, specifically so that an ARP broadcast sent by a customer in VLAN 10 does not reach devices in VLAN 20. What has effectively been created between the two VLANs?
• A new subscriber's router sends its first Ethernet frame through a rural cooperative's access switch. The switch has never seen that device's source MAC address before. What does the switch do with that address as part of its normal learning behavior?
• A cooperative's NOC notices that a frame destined for a subscriber's set-top box is being sent out every port on an access switch except the one it arrived on, even though the box has been online and streaming for weeks without issue. What is the most likely explanation for this flooding behavior?
• A rural ISP's access switch periodically removes MAC address table entries for ports that have not sent traffic for a while. What is this behavior called, and why does it matter operationally?
• A rural cooperative wants to deliver a live IPTV channel to every subscriber set-top box that has tuned in across a town, without sending a separate copy of the stream to each individual subscriber and without sending it to devices that never asked for it. Which traffic delivery type best fits this requirement?
• A cooperative's engineer is choosing transport behavior for a live voice call between two rural offices, where a small amount of dropped audio is acceptable but delay caused by session setup or retransmissions is not. Which category of transport protocol behavior best fits this requirement?
• A rural ISP's billing server and its remote-monitoring server both send traffic to the same head-end router at the same time. What allows the receiving system to correctly sort the arriving segments and deliver each stream to the right application?
• A subscriber's laptop at a rural cooperative receives an Ethernet frame carrying a web page from a regional data center. As that frame moves up through the receiving device's protocol stack toward the browser, what happens to it?
• A cooperative's new hire is studying networking fundamentals and needs to understand how the four-layer TCP/IP model relates to the seven-layer OSI model. Which statement correctly describes that relationship?
• A technician auditing a rural cooperative's newly upgraded access layer notes that every subscriber port now connects to a dedicated switch port running full-duplex, with the old shared hubs removed entirely. What effect does this have on collisions for those links?
• A rural cooperative's regional hub site connects two separate towns through a router, with each town's subscribers on its own switched network behind that router. When a subscriber in Town A sends an ARP broadcast, what happens to it at the router?
• A junior technician at a cooperative's NOC sees an access switch send a frame out every port for an unknown destination MAC address, and separately sees a subscriber's DHCP discover frame also go out every port. The technician assumes these are the same behavior. Why are they actually different?
• A rural ISP's back-office application requires guaranteed, in-order delivery of every byte between two servers exchanging subscriber billing records, including automatic retransmission of anything lost in transit. Which transport behavior category provides this?
• A cooperative's engineer needs to double-check a hand-written subnet mask octet before typing it into a router, and the paper shows the binary value 11111000. What is this value in decimal?
• While training a new NOC hire, a senior technician at a rural cooperative draws the path a subscriber's file download takes: the data is handed to the transport layer, then the network layer, then the data link layer, before going out on the fiber. The new hire asks what the unit of data is called at each of those layers. In order, what should the technician say?
• A rural broadband cooperative has been allocated the 10.20.0.0/22 block for a new fiber build and wants to give each of its 16 villages its own separate subnet with room for up to 60 subscriber devices per village. Which subnet mask satisfies both requirements with no wasted subnets?
• A regional ISP's four contiguous head-end blocks — 192.168.4.0/24, 192.168.5.0/24, 192.168.6.0/24, and 192.168.7.0/24 — are all reachable through the same upstream transit router. Which single summary route advertises exactly this address range and nothing more, letting the ISP send one route to its peering partner instead of four?
• A subscriber-aggregation router at a co-op's POP holds three routes toward a destination address of 203.0.113.45: 203.0.113.0/24, 203.0.113.32/27, and a default route of 0.0.0.0/0 pointing to the transit provider. Which route does the router actually use to forward the packet?
• A cooperative's regional office assigns the subnet 172.16.14.96/27 to its NOC workstations. A technician needs to configure a new monitoring server at 172.16.14.110. Which statement correctly describes this address's position within the subnet?
• While documenting the co-op's new IPv6 rollout, an engineer captures three addresses in use on a POP router: fe80::1, ff02::1, and 2001:db8:abcd::1. Which statement correctly matches each address to its IPv6 address type?
• A new POP needs four subscriber VLANs carved out of 10.10.8.0/24: one for 100 residential subscribers, one for 50 business subscribers, and two management VLANs needing 25 hosts each. Using VLSM, which mask set correctly provides just enough usable addresses for each group without unnecessary waste?
• A cooperative's operations team receives a single 10.30.0.0/20 block to allocate across its rural fiber region and plans to hand each of its distribution cabinets a full /24 subnet. How many separate /24 subnets can be carved out of this /20 allocation?
• Two POPs in a rural fiber ring are connected by a dedicated point-to-point fiber link that only ever needs to number two router interfaces, one at each end. Which subnet mask is the most address-efficient choice for this link?
• A cooperative's IPv6 planning team receives a single 2001:db8:abcd::/48 allocation from its upstream provider and wants to give every village in its territory its own separate /64 subnet, the standard size for a single IPv6 LAN segment. How many distinct /64 subnets can this /48 allocation support?
• A distribution cabinet is being planned to serve approximately 400 subscriber CPE devices on a single flat subnet, drawn from a spare 10.5.0.0/16 block. Which subnet mask correctly provides enough usable addresses for this cabinet without requiring the subnet to be split further?
• A cooperative is designing IPv6 addressing for its internal back-office network — device management interfaces, NOC servers, and internal monitoring links that must never be reachable from the public internet. Which type of IPv6 address is the appropriate choice for this internal-only addressing plan?
• A cooperative's back-office workstations use private 10.x addresses internally, but a technician notices that when one of those workstations reaches a public website, the site's server sees a completely different, publicly routable source address in the arriving packets. Which function performed this address change?
• A cooperative's shared uplink occasionally gets busy enough that a live voice call's audio packets and a subscriber's large file download are both waiting to leave the same interface at once. Which general networking concept lets time-sensitive voice packets get serviced ahead of the bulk transfer instead of waiting in strict arrival order?
• A regional ISP owns three head-end blocks for route advertisement to its upstream peer: 192.168.8.0/24, 192.168.9.0/24, and 192.168.11.0/24. The block in between, 192.168.10.0/24, belongs to a different provider and is not part of this ISP's allocation. Which route advertisement correctly summarizes what the ISP can safely send upstream?
• An engineer is documenting a POP router's loopback address for the NOC runbook and has the fully expanded IPv6 address 2001:0db8:0000:0000:0000:0000:0000:0001. Which of the following is the correctly compressed form of this same address?
• A NOC technician is assigned the subnet 10.50.5.64/26 for a new equipment cabinet and needs to confirm the subnet's usable address boundaries before assigning device addresses. Which pair of addresses correctly marks the first and last usable host addresses in this subnet?
• At a small-town head-end, a technician needs to connect a printer and a workstation that both sit on the same subnet, and separately needs to let a NOC server on a different subnet reach a monitoring host on yet another subnet across the POP. Which statement correctly matches each need to the right forwarding function?
• A cooperative's engineering team wants to divide its 10.60.0.0/22 rural fiber allocation into eight equally sized subnets, one for each village PoP along a new fiber ring, with each village needing up to 100 subscriber addresses. Which mask correctly creates exactly eight equal subnets from this /22 block while still meeting the per-village host requirement?