2.0 Network Implementation N10-009 Practice Quiz

• A. A static route is a manually configured route that tells the router how to reach a specific destination network, it does not change unless an administrator modifies it; static routes are most appropriate for small stable networks with few routes, stub networks with only one path to the rest of the network, and providing a default route (0.0.0.0/0) to the internet
• B. A static route is a route that automatically updates when network topology changes, the routing table refreshes every 30 seconds to reflect current network conditions without administrator intervention
• C. A static route is a route learned from a neighboring router using the OSPF protocol, the word static refers to the fact that OSPF routes do not change unless the OSPF database is refreshed
• D. A static route is only used in IPv6 networks, IPv4 routing exclusively uses dynamic routing protocols while IPv6 supports both static and dynamic routing

Static routes are manually configured entries in the routing table specifying a destination network, subnet mask, and next-hop address or exit interface, they are ideal for stub networks (one path in/out), point-to-point WAN links, default routes to internet gateways, and small networks where the simplicity of static routing outweighs the management overhead. This is the correct answer.

• A. OSPF and EIGRP are Interior Gateway Protocols (IGPs) used for routing within a single organization's network (autonomous system); BGP is an Exterior Gateway Protocol (EGP) used for routing between autonomous systems, BGP is the protocol of the internet backbone exchanging routes between ISPs and large organizations; OSPF is link-state and vendor-neutral; EIGRP is advanced distance-vector and Cisco-proprietary (now open standard)
• B. OSPF is used for IPv6 only; EIGRP is used for IPv4 only; BGP supports both, the protocol choice is determined by the IP version deployed in the network
• C. OSPF handles Layer 2 switching; EIGRP handles Layer 3 routing; BGP handles Layer 4 transport, each protocol operates at a different OSI layer managing different aspects of network communication
• D. All three protocols are identical in function but preferred by different geographic regions, OSPF is preferred in North America, EIGRP in Europe, and BGP in Asia; organizations choose based on vendor support in their region

The IGP vs. EGP distinction defines the primary use case, OSPF (Open Shortest Path First) uses link-state algorithms to build a topology map within one AS; EIGRP (Enhanced Interior Gateway Routing Protocol) uses a diffusing computation algorithm within one AS; BGP (Border Gateway Protocol) is the only widely deployed EGP, exchanging routing information between autonomous systems at internet scale using path attributes for policy control. This is the correct answer.

• A. Traffic automatically fails over to the OSPF route via 192.168.1.2, static routes automatically yield to dynamic routes when the static route's next-hop becomes unreachable; OSPF reconvergence provides seamless failover
• B. Both routes are removed from the routing table, when any route to a destination becomes unreachable the router removes all routes to that destination regardless of their source
• C. Traffic is dropped, the static route has a lower administrative distance (1) than OSPF (110) meaning it is preferred; the static route remains in the routing table even though the network is unreachable; the router continues sending traffic via 192.168.1.1 into the failed network; this illustrates the limitation of static routes, they do not adapt to topology changes unlike dynamic routing protocols
• D. The router uses load balancing, it splits traffic equally between the static route via 192.168.1.1 and the OSPF route via 192.168.1.2; 50% of packets reach the destination and 50% are dropped

The static route with AD 1 is preferred over OSPF with AD 110, since the static route is still present in the routing table (the router can still reach next-hop 192.168.1.1 even if the ultimate destination is unreachable), traffic continues forwarding to a black hole; this illustrates why static routes require careful management and why floating static routes (configured with higher AD than the primary dynamic protocol) are used for backup purposes. This is the correct answer.

• A. Configure the static route with administrative distance 1 (default for static routes), since 1 is lower than OSPF's 110, the static route will be preferred and OSPF will serve as backup
• B. Floating static routes require enabling track objects, the static route must be linked to an IP SLA track that monitors the OSPF neighbor; without tracking the floating static route feature does not activate during OSPF failures
• C. Configure the static route with administrative distance 0, AD 0 is a reserved value that tells the router to use this route only when no other routes exist; it provides automatic failover behavior for backup routing
• D. Configure the static route with administrative distance 111 or higher, a floating static route uses an AD higher than the primary dynamic routing protocol (OSPF AD 110); when OSPF is operational the OSPF route (AD 110) is installed in the routing table; the static route (AD 111) is suppressed; when OSPF fails and the dynamic route is removed the floating static route is installed as the backup path

A floating static route uses an AD greater than the primary protocol, when OSPF is active, the OSPF route (AD 110) wins and the static route (AD 111 or higher) is not installed in the routing table; when OSPF fails and removes its route, the floating static route with AD 111 is installed as the backup; the AD must be higher than 110 for OSPF to remain primary. This is the correct answer.

• A. OSPF converges faster than EIGRP in all network scenarios, OSPF's HELLO interval is always shorter than EIGRP's making it the universally preferred choice for hub-and-spoke networks where fast failover is critical
• B. OSPF requires more memory than EIGRP for the same topology, OSPF stores a complete link-state database requiring all routers to maintain a full topology map; EIGRP uses a simpler distance-vector approach storing only neighbor routes; in a memory-constrained environment EIGRP has lower RAM requirements
• C. OSPF and EIGRP have identical convergence behavior, the metric calculation method does not affect how quickly either protocol responds to topology changes; the enterprise should choose based solely on which protocol the network team is more familiar with
• D. EIGRP requires Cisco hardware at all locations while OSPF is vendor-neutral, if any location uses non-Cisco equipment OSPF must be used; if all locations use Cisco equipment EIGRP is preferred because it converges faster and supports unequal-cost load balancing which OSPF does not support

Vendor neutrality is a critical differentiator, EIGRP was Cisco-proprietary for decades (now an IETF informational RFC but still primarily Cisco-implemented); if the enterprise has multi-vendor equipment OSPF is required; EIGRP's unequal-cost load balancing (variance command) is a genuine advantage over OSPF for traffic engineering in hub-and-spoke designs. This is the correct answer.

• A. Static routes cannot be used across WAN links, they only function on LAN segments within the same broadcast domain; WAN connections require dynamic routing protocols regardless of network size
• B. Static routes to 50 branches would require manually adding and maintaining entries for every subnet at every branch, when a new branch is added or a branch's subnets change every static route at headquarters must be manually updated; human error in route configuration causes traffic black holes; there is no automatic convergence if a branch WAN link fails; the operational overhead grows linearly with branch count; dynamic routing protocols automate this with negligible additional configuration per new site
• C. Static routes consume more CPU on headquarters routers than dynamic routing protocols, each static route requires a dedicated CPU thread for constant monitoring making 50 static routes computationally intensive for enterprise routers
• D. Static routes prevent the use of DHCP at branch offices, when static routes exist on the hub router all branch devices must use statically assigned IP addresses; DHCP is incompatible with static routing at the WAN edge

Manual management burden and lack of automatic convergence are the core problems with static routing at scale, with 50 branches and potentially multiple subnets per branch the administrator must maintain potentially hundreds of static routes; any change requires manual intervention at headquarters; a failed WAN link creates a black hole that persists until an administrator removes or corrects the static route; dynamic routing automates all of this. This is the correct answer.

• A. Internal BGP (iBGP) is used between the ISP's routers and External BGP (eBGP) is used between the ISP and its upstream providers, eBGP sessions are established between routers in different autonomous systems (different ASNs) and are typically between directly connected routers; iBGP sessions are between routers within the same AS and distribute externally learned routes throughout the organization
• B. Active BGP (aBGP) is used for primary upstream connections and Passive BGP (pBGP) is used for backup connections, the ISP establishes active sessions to two providers and passive sessions to one; passive BGP requires no configuration on the ISP's router
• C. Public BGP (pBGP) is used for routing to internet destinations and Private BGP (prBGP) is used for routing to the ISP's internal customers, the distinction is based on whether the destination is publicly or privately addressed
• D. There is only one type of BGP, the internal vs. external distinction is a configuration option within a single protocol; iBGP and eBGP sessions are identical in operation and only differ in which ASN they announce to neighboring routers

iBGP and eBGP are the two fundamental BGP session types, eBGP (External BGP) runs between routers in different autonomous systems (different AS numbers); the ISP establishes eBGP sessions with each of the three upstream providers exchanging full internet routing tables; iBGP (Internal BGP) distributes externally learned routes among the ISP's own internal routers; iBGP has different loop prevention rules (requiring full mesh or route reflectors) since the AS_PATH loop prevention used by eBGP doesn't apply internally. This is the correct answer.

• A. The shortcut link fails because OSPF requires all area links to use fiber optic connections, copper links between areas are not supported in multi-area OSPF designs
• B. OSPF's two-layer hierarchy requires all inter-area traffic to traverse area 0, a direct area 1 to area 2 link creates a 'virtual backdoor' that OSPF's design prevents from being used for inter-area routing; OSPF will not advertise inter-area routes through a non-backbone path because all area border routers must connect to area 0 for proper route calculation; the solution is a virtual link through area 0 or redesigning the area topology
• C. The shortcut link fails because EIGRP must be used for direct area-to-area links, OSPF handles only backbone connections while EIGRP handles non-backbone inter-area connectivity in multi-vendor environments
• D. The shortcut works but only for unicast traffic, multicast and broadcast traffic between area 1 and area 2 still traverses area 0; the engineer must enable OSPF multicast on the direct link for full inter-area functionality

OSPF's backbone area requirement is a fundamental design constraint, area 0 is the backbone and all other areas must connect to it; inter-area routing always goes through area 0 because ABRs (Area Border Routers) only generate inter-area routes via the backbone; a direct area 1 to area 2 link creates an intra-area link within those areas but cannot carry inter-area summary routes because OSPF's SPF calculation does not allow non-backbone inter-area paths; this is by design to prevent routing loops. This is the correct answer.