Unit 4: Network layer - Practice Quiz

1 Which IPv4 address class has a first-octet range from 1 to 126?

2 What is the default subnet mask of a Class C network?

3 Which statement correctly describes a private IPv4 address?

4 Which address belongs to a private IPv4 address range?

5 What is the primary function of NAT?

6 Which is a common benefit of using NAT?

7 How is a static route usually added to a router?

8 For which type of network is static routing generally most suitable?

9 What do dynamic routing protocols allow routers to do?

10 What is a key advantage of dynamic routing over static routing?

11 What information does a distance vector router commonly share with neighboring routers?

12 In distance vector routing, what does the term "distance" represent?

13 Which metric does RIP use to select routes?

14 What is the maximum usable hop count in RIP?

15 What does a link state router build to calculate routes?

16 Which algorithm is commonly associated with link state routing?

17 What type of routing protocol is OSPF?

18 Which metric does OSPF use when selecting a route?

19 Which IPv4 prefix represents the default route?

20 When does a router normally use its default route?

21 A host has the classful IPv4 address 172.18.45.9. Without subnetting, which part identifies its network?

22 An organization is assigned the Class C network 200.10.8.0. How many usable host addresses are available if the default classful mask is used?

23 Which host can use its assigned address on a private LAN without requiring the address to be globally unique on the Internet?

24 A company assigns 172.31.250.4 to an internal server. Which statement correctly describes this address?

25 Three internal hosts simultaneously access the same web server through one public IPv4 address. How does Port Address Translation keep their sessions distinct?

26 An internal web server at 192.168.1.20 must always be reachable through public address 203.0.113.20. Which NAT configuration best fits this requirement?

27 Router R1 reaches network 192.168.40.0/24 through neighboring router 10.0.0.2. Which static route is appropriate on R1?

28 A backup static route is configured with a higher administrative distance than the primary route. When will the backup route enter the routing table?

29 A network frequently adds links and experiences occasional failures. What is the main operational advantage of dynamic routing over only static routing?

30 A router learns the same destination from two routing protocols. What value is generally compared first to choose between routes learned from different protocol sources?

31 After a link failure, neighboring routers repeatedly advertise increasing metrics for an unreachable network. Which distance vector problem is occurring?

32 Router A learned a route to network N from Router B. Under split horizon, what should Router A do when sending an update back to Router B?

33 RIP learns two routes to the same destination: one with 3 hops over a slow link and one with 5 hops over a fast link. Which route does RIP normally select?

34 A destination is reported with a hop count of 16 in RIP. How does a RIP router interpret that destination?

35 After receiving updated link-state information, what does a link-state router do to determine its preferred routes?

36 Why must routers in the same link-state area maintain synchronized link-state databases?

37 An OSPF router can reach a network through Path X with costs 10, 5, and 20, or Path Y with costs 15 and 15. Which path is selected?

38 A multiarea OSPF design contains areas 0, 1, and 2. What is the primary role of area 0?

39 A router has routes for 10.1.0.0/16, 10.1.2.0/24, and 0.0.0.0/0. Which route is used for a packet addressed to 10.1.2.50?

40 A branch router has one WAN connection to headquarters and several directly connected LANs. Why is a default route suitable for unknown remote destinations?

41 A router using strictly classful addressing receives a packet destined for 126.200.3.4. Which network address, directed broadcast address, and maximum usable host count apply?

42 Assuming the only exclusions being tested are the RFC 1918 private ranges, which address is eligible to be globally routed as a public unicast address?

43 A NAT device has a pool of eight public IPv4 addresses and uses only dynamic one-to-one NAT, without port translation. If every active internal host requires simultaneous Internet access, what is the maximum number of internal hosts that can be represented concurrently?

44 Two internal hosts simultaneously send TCP connections using the same source port to the same external server and destination port. Under PAT, how can the NAT device keep both flows distinct while using one public IPv4 address?

45 An IPv4 TCP packet is fragmented before reaching a NAT device. Only the first fragment contains the TCP header. What capability is needed for the NAT device to translate the later fragments consistently?

46 A router contains ip route 203.0.113.0/24 192.0.2.9 and ip route 192.0.2.0/24 Serial0. Assuming both routes are active, how is a packet for 203.0.113.25 forwarded?

47 A router learns 198.51.100.0/24 through OSPF with administrative distance 110. Which static route acts as a floating backup and becomes active only after the OSPF route disappears?

48 For the same destination prefix, a router has a static route with administrative distance 1, an OSPF route with distance 110, and a RIP route with distance 120. The RIP route has the numerically smallest protocol metric. Which route is installed?

49 Why can poison reverse fail to eliminate every routing loop in a distance-vector network containing three or more routers?

50 Router X has link cost 4 to A and link cost 1 to B. A advertises distance 3 to destination D, while B advertises distance 7. After applying the Bellman-Ford rule, which route does X choose?

51 A RIP router receives an advertisement reporting metric 15 for a destination from a directly connected neighbor. What metric does the receiving router assign to the candidate route?

52 Two sites use subnets 10.1.0.0/16 and 10.2.0.0/16, separated by a transit network from another classful major network. Why can RIPv1 cause reachability problems in this discontiguous design?

53 A RIP router currently reaches network N through R1 at metric 2. It then receives an advertisement of metric 10 from R1 and metric 5 from R2. Assuming one hop is added to each received metric, what route should ultimately be preferred?

54 After a temporary partition, a router receives an old link-state advertisement and a newer advertisement for the same origin. Which mechanism primarily prevents the old information from replacing the newer topology state?

55 A link-state router A has links A-B of cost 2 and A-C of cost 5. Additional links are B-C of cost 1, B-D of cost 7, and C-D of cost 3. What shortest-path cost does Dijkstra's algorithm compute from A to D?

56 On an OSPF broadcast network, routers R1 and R2 are already DR and BDR. R3 then joins with a higher interface priority than both. No failures occur. What is the immediate election result?

57 With the traditional OSPF reference bandwidth of 100 Mbps and integer interface costs, what problem occurs when both 1 Gbps and 10 Gbps links use default cost calculation?

58 An OSPF router learns the same prefix as an intra-area route with cost 50 and as an external route with a seemingly lower calculated cost of 10. Which route type is preferred?

59 A routing table contains 0.0.0.0/0 via A, 192.0.0.0/16 via B, and 192.0.2.0/24 via C. Through which next hop is a packet for 192.0.2.200 forwarded?

60 A router learns 0.0.0.0/0 from OSPF with administrative distance 110, from RIP with distance 120, and from a floating static route with distance 200. Assuming all are otherwise valid, which default route is installed?