IP Connectivity

493 soru

Soru 1Soru

Match each OSPFv2 network type or interface configuration on the left to its corresponding DR/BDR election requirement and default timer profile on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Broadcast
Point-to-Point
Point-to-Multipoint
OSPF Interface Priority set to 0

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Broadcast pairs with DR/BDR election and 10s/40s timers; Point-to-Point pairs with no DR/BDR election and 10s/40s timers; Point-to-Multipoint pairs with no DR/BDR election and 30s/120s timers; Priority 0 explicitly excludes the interface from DR/BDR election.
Broadcast network types perform DR/BDR elections with 10s/40s timers to minimize link-state information flooding across shared multiaccess media. Point-to-Point network types suppress DR/BDR elections since only two endpoints exist, using 10s/40s timers. Point-to-Multipoint network types also suppress DR/BDR elections but use 30s/120s timers suitable for WAN connections. Configuring an OSPF priority of 0 explicitly forces the interface to act strictly as a DROther, avoiding DR or BDR role assignment.

Adım Adım Çözüm

1
Identify network types that perform DR/BDR elections
Only Broadcast (and Non-Broadcast Multiaccess / NBMA) network types conduct DR/BDR elections.
Multiaccess segments require a central router (DR) to reduce adjacency overhead from n(n-1)/2 to n-1.
2
Differentiate default Hello and Dead timers among non-DR network types
Point-to-Point uses 10s Hello / 40s Dead timers, whereas Point-to-Multipoint uses 30s Hello / 120s Dead timers.
Point-to-Multipoint is designed for hub-and-spoke topologies where slower timers account for WAN link characteristics.
3
Determine the impact of setting interface priority to 0
An OSPF priority of 0 disqualifies the interface from becoming DR or BDR.
The priority range is 0-255, where 0 explicitly excludes the router from election, keeping it as a DROther regardless of Router ID.

Anahtar Kavram

OSPFv2 Network Types and DR/BDR Selection Rules
Soru 2Soru

When a router processes an incoming IP packet to make a forwarding decision, it evaluates matching candidate routes using a deterministic precedence hierarchy. Place the following routing decision criteria in the correct order of evaluation from first (1st) to last (4th).

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Cevap

The correct sequence for router forwarding decision logic is: 1) Longest prefix match, 2) Administrative distance, 3) Metric, and 4) Equal-cost load balancing.
A router evaluates forwarding decisions using a strict hierarchy: first, it determines the longest prefix match (most specific subnet mask matching the destination IP). If multiple routes have the exact same prefix length, it evaluates Administrative Distance to select the route from the most trustworthy source. If multiple routes come from the same routing source with identical prefix lengths, it compares the Metric to pick the path with the lowest cost. Finally, if prefix length, Administrative Distance, and Metric are all equal, the router performs equal-cost load balancing.

Adım Adım Çözüm

1
Evaluate subnet mask specificity for candidate routes matching the destination IP.
Longest prefix match is evaluated first.
The router always prefers the most specific route (longest prefix length) regardless of protocol or AD.
2
Compare routing sources when matching routes have identical prefix lengths.
Administrative Distance (AD) is evaluated second.
Lower AD indicates a more believable/trustworthy routing source (e.g., Static route AD 1 vs OSPF AD 110).
3
Compare route metrics for paths learned via the same routing protocol with identical prefix lengths.
Metric is evaluated third.
Within a single routing protocol, lower metric indicates a lower-cost, more efficient network path.
4
Handle remaining candidate routes where prefix length, AD, and metric are all identical.
Equal-cost load balancing is applied fourth.
When all criteria are tied, the router installs multiple next-hops into the forwarding table for traffic sharing.

Anahtar Kavram

Router Forwarding Precedence Hierarchy
Soru 3Soru

Refer to the following routing table output from a Cisco router:

Codes: C - connected, S - static, R - RIP, O - OSPF
Gateway of last resort is not set

10.0.0.0/8 is subnetted, 4 subnets
O 10.1.1.0/24 [110/20] via 192.168.1.2, 00:04:12, GigabitEthernet0/0
S 10.1.0.0/16 [1/0] via 192.168.1.1, GigabitEthernet0/1
O 10.1.1.128/25 [110/30] via 192.168.1.3, 00:02:15, GigabitEthernet0/2
S* 0.0.0.0/0 [1/0] via 192.168.1.254

When the router receives a packet destined for host 10.1.1.130, which next-hop IP address will the router use to forward the packet?

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Cevap: 192.168.1.3

Cevap

The router will forward the packet to next-hop 192.168.1.3.
When a router makes a forwarding decision, it evaluates all routes in the routing table that cover the destination address and selects the one with the longest prefix mask (most specific match). Destination host 10.1.1.130 matches 10.1.0.0/16, 10.1.1.0/24, and 10.1.1.128/25. The route 10.1.1.128/25 is the most specific match with 25 matching bits, so the router forwards the packet to its next-hop IP address, 192.168.1.3.

Adım Adım Çözüm

1
Identify all matching routes for destination IP address 10.1.1.130.
Matching routes are 10.1.0.0/16, 10.1.1.0/24, 10.1.1.128/25, and 0.0.0.0/0.
10.1.1.130 falls within the range of 10.1.0.0–10.1.255.255 (/16), 10.1.1.0–10.1.1.255 (/24), 10.1.1.128–10.1.1.255 (/25), and default route.
2
Compare prefix lengths of all matching routes to determine the Longest Prefix Match (LPM).
10.1.1.128/25 has a 25-bit subnet mask, which is longer than /24, /16, and /0.
The router always prefers the route with the most specific (longest) prefix match before considering Administrative Distance or Metric.
3
Identify the next-hop address associated with the longest prefix match route.
The route 10.1.1.128/25 uses next-hop 192.168.1.3.
The forwarding table specifies via 192.168.1.3 for 10.1.1.128/25.

Anahtar Kavram

Longest Prefix Match (LPM) Rule
Tahmini Süre:1m 0s
Soru 4Soru

Refer to the exhibit displaying an abbreviated routing table for router R1:

text
Gateway of last resort is 192.168.4.1 to network 0.0.0.0

S* 0.0.0.0/0 [1/0] via 192.168.4.1, Serial0/0/0
S 10.1.1.0/24 [1/0] via 192.168.1.1, GigabitEthernet0/0
D 10.1.1.64/26 [90/307200] via 192.168.2.1, GigabitEthernet0/1
O 10.1.1.64/28 [110/20] via 192.168.3.1, GigabitEthernet0/2

Router R1 receives an IP packet addressed to destination host 10.1.1.6710.1.1.67. Which next-hop IP address and outbound interface will R1 use to forward this packet?

Cevabı ve açıklamayı göster

Cevap: 192.168.3.1 via GigabitEthernet0/2

Cevap

192.168.3.1 via GigabitEthernet0/2
When forwarding a packet, a router first evaluates all routes in its routing table to find matches for the destination IP address. If multiple routes match, the router strictly enforces the Longest Prefix Match (LPM) rule. For destination IP 10.1.1.67, matching prefixes are /24, /26, and /28. The /28 prefix (10.1.1.64/28) is the longest match. Therefore, R1 forwards the packet to next-hop 192.168.3.1 via interface GigabitEthernet0/2, completely ignoring Administrative Distance when prefix lengths differ.

Adım Adım Çözüm

1
Determine subnet ranges for matching routes in the routing table for destination IP 10.1.1.6710.1.1.67
The IP 10.1.1.6710.1.1.67 matches three specific routes: 10.1.1.0/24 (range .0 to .255), 10.1.1.64/26 (range .64 to .127), and 10.1.1.64/28 (range .64 to .79), as well as the default route 0.0.0.0/0.
Before comparing routing protocols or metrics, a router determines which routes encompass the destination IP address.
2
Compare matching prefix lengths to apply the Longest Prefix Match (LPM) rule
Prefix lengths are /24, /26, and /28. The /28 prefix length is the longest (most specific) match.
Cisco routers always prefer the route with the longest matching subnet mask (/28 > /26 > /24 > /0) regardless of Administrative Distance or Metric.
3
Identify the next-hop IP address and egress interface for the winning /28 route
The route `10.1.1.64/28` points to next-hop IP `192.168.3.1` out interface `GigabitEthernet0/2`.
The parameters associated with the longest prefix match determine the forwarding destination for the packet.

Anahtar Kavram

Router Forwarding Decision Logic & Longest Prefix Match (LPM)
Tahmini Süre:1m 30s
Soru 5Soru

An engineer wants to configure a floating static route on a Cisco router to serve as a backup for a primary route learned via OSPF (Administrative Distance 110). Which two statements correctly describe the requirements and operational behavior of this floating static route?

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Cevap: The administrative distance assigned to the floating static route must be set higher than 110.; The floating static route will remain inactive and out of the routing table as long as the primary OSPF route is active.

Cevap

The floating static route must be configured with an administrative distance greater than 110, and it will remain inactive in the routing table while the primary OSPF route is operational.
A floating static route functions as a backup and must be configured with an administrative distance higher than that of the active primary routing protocol (OSPF AD 110). Because Cisco routers select routes with lower administrative distance values for forwarding, the floating static route remains hidden from the routing table until the primary OSPF route fails.

Adım Adım Çözüm

1
Determine the administrative distance of the primary route.
OSPF has a default administrative distance of 110.
To create a floating static backup route, the configured administrative distance must be higher than that of the primary route.
2
Analyze router path selection logic.
The router selects the route with the lowest administrative distance for installation into the active routing table.
Because the static route's administrative distance is higher than 110, it stays out of the routing table until the primary OSPF route disappears.

Anahtar Kavram

Floating Static Route Administrative Distance Requirements
Tahmini Süre:1m 0s
Soru 6Soru

A network engineer is configuring a backup floating IPv6 static route on router R1 toward destination prefix 2001:db8:7410:a1::/642001:\text{db8}:7410:\text{a1}::/64. The next-hop router is identified by its link-local address fe80::cafe:1\text{fe80}::\text{cafe}:1 over local interface GigabitEthernet0/0/0\text{GigabitEthernet0/0/0}. The route must be configured with an administrative distance of 140140. Fill in the missing parameters in the command snippet below.

Aşağıdaki boşlukları doldurun

R1(config)# ipv6 route 2001:db8:7410:a1::/64 fe80::cafe:1
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Cevap

The first blank requires specifying the local exit interface GigabitEthernet0/0/0, and the second blank requires the administrative distance value of 140.
When configuring an IPv6 static route using a link-local address as the next-hop, Cisco IOS strictly requires the explicit specification of the local exit interface. The syntax is 'ipv6 route <prefix/mask> <exit-interface> <link-local-address> [AD]'. Therefore, the first blank requires the local interface GigabitEthernet0/0/0, and the second blank requires the administrative distance of 140.

Adım Adım Çözüm

1
Identify the mandatory components of a fully-specified IPv6 static route using a link-local address.
When a link-local address (fe80::/10) is used as the next-hop IPv6 address, the exit interface must be specified because link-local addresses are only unique to the local link.
Without an exit interface, Cisco IOS cannot resolve which interface to send traffic out of when using a link-local address.
2
Determine the position of the exit interface parameter in the command syntax.
The correct command syntax is: ipv6 route <destination-prefix/prefix-length> <exit-interface> <link-local-next-hop> [administrative-distance].
The exit interface GigabitEthernet0/0/0 fills the position immediately following the destination IPv6 prefix.
3
Identify the position of the floating administrative distance parameter.
The administrative distance value of 140 is placed at the end of the command string.
Setting an administrative distance higher than the default static route distance of 1 makes this route a floating static backup route.

Anahtar Kavram

IPv6 Static Route Syntax with Link-Local Next-Hop and Administrative Distance
Tahmini Süre:1m 30s
Soru 7Soru

An enterprise router has populated its IPv4 routing table with the following entries:

text
D 10.50.0.0/16 [90/2560512] via 10.1.1.1, 01:12:40, GigabitEthernet0/0
O 10.50.12.0/24 [110/20] via 10.1.1.2, 00:45:12, GigabitEthernet0/1
S 10.50.12.80/28 [1/0] via 10.1.1.3
S 10.50.12.80/29 [250/0] via 10.1.1.4

The router receives a packet with a destination IP address of 10.50.12.8510.50.12.85. Which next-hop IP address will the router select to forward this packet?

Cevabı ve açıklamayı göster

Cevap: 10.1.1.4

Cevap

10.1.1.4 via the longest prefix match route 10.50.12.80/29
When a router processes a packet destination address, it searches the routing table for all matching network prefixes and selects the route with the longest prefix length (most specific mask). The destination address 10.50.12.85 falls within the range 10.50.12.80 - 10.50.12.87 defined by 10.50.12.80/29. Because /29 is longer than /28, /24, and /16, the router forwards the packet using the next-hop 10.1.1.4 regardless of its high administrative distance value of 250.

Adım Adım Çözüm

1
Determine which routing table entries match the destination IP address 10.50.12.85.
All four entries (10.50.0.0/16, 10.50.12.0/24, 10.50.12.80/28, and 10.50.12.80/29) contain the IP address 10.50.12.85 within their subnet range.
10.50.12.80/29 spans 10.50.12.80 through 10.50.12.87, which includes 10.50.12.85.
2
Compare the prefix lengths (subnet masks) of all matching entries.
/29 is longer (more specific) than /28, /24, and /16.
Cisco routers use the Longest Prefix Match (LPM) rule as the primary criteria for forwarding decisions.
3
Identify the next-hop address associated with the longest matching prefix.
The route 10.50.12.80/29 points to next-hop 10.1.1.4.
Administrative distance is only evaluated when comparing routes with identical prefix lengths from different sources, not when selecting among matching routes of varying prefix lengths.

Anahtar Kavram

Longest Prefix Match (LPM) rule in IPv4 routing decision logic
Tahmini Süre:1m 15s
Soru 8Soru

A network technician is adding a secondary path on Router-HQ to reach the internal subnet 172.16.40.0/24172.16.40.0/24. The primary link currently learns this destination via EIGRP with an administrative distance of 90. To ensure the secondary static path through next-hop IP 10.1.1.210.1.1.2 serves strictly as a backup when the primary link is down, which Cisco IOS command must be configured?

Cevabı ve açıklamayı göster

Cevap: ip route 172.16.40.0 255.255.255.0 10.1.1.2 100

Cevap

The command 'ip route 172.16.40.0 255.255.255.0 10.1.1.2 100' correctly configures a floating static route by specifying an administrative distance higher than the primary routing protocol.
A floating static route functions as a backup path by configuring an administrative distance (AD) higher than the primary active route's protocol. Since the primary route is learned via internal EIGRP (AD 90), assigning an AD of 100 to the static route keeps it out of the active routing table until the EIGRP path becomes unavailable.

Adım Adım Çözüm

1
Identify the primary route's Administrative Distance (AD)
EIGRP internal route has an AD of 90.
Floating static routes rely on AD values to determine precedence.
2
Determine the required AD for a floating static backup route
The floating static route must have an AD strictly greater than 90 (e.g., 100).
Lower administrative distances are preferred in the IP routing table.
3
Construct the Cisco IOS static route command syntax
'ip route <destination> <mask> <next-hop> [administrative-distance]'
Applying this syntax yields 'ip route 172.16.40.0 255.255.255.0 10.1.1.2 100'.

Anahtar Kavram

Floating Static Route Administrative Distance Calibration
Soru 9Soru

A Cisco router receives an IP packet and initiates a route lookup process to select the optimal path. Arrange the router forwarding decision logic steps in the correct sequential order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

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Cevap

The correct sequence for router forwarding decision logic is: 1) Identify matching routing table entries, 2) Select the route with the Longest Prefix Match, 3) Break ties using Administrative Distance for different sources, 4) Break ties using Metric for identical sources, and 5) Forward the packet using the selected next-hop/exit interface.
The router forwarding process strictly follows a hierarchical evaluation sequence: First, the router checks for matching network entries in the routing table. Second, if multiple matching routes exist, it selects the route with the Longest Prefix Match (LPM), which represents the most specific path. Third, if multiple routes have the exact same prefix length but come from different sources, the router uses Administrative Distance (AD) to select the most reliable source. Fourth, if the prefix length and routing source are the same, the router uses the protocol's Metric to choose the optimal path. Finally, the packet is forwarded out the resulting egress interface to the next-hop IP.

Adım Adım Çözüm

1
Scan routing table for matching prefix entries
Candidate routes matching the destination IP address are identified
The router performs a bitwise AND operation on the destination IP with subnet masks in the table to find matches.
2
Apply Longest Prefix Match (LPM) rule
The candidate route with the longest mask length is prioritized above all others
LPM takes precedence over Administrative Distance and Metric regardless of the routing protocol source.
3
Compare Administrative Distance (AD)
Ties between identical prefix lengths from different routing protocols are broken
Lower AD indicates a more believable/trustworthy route source (e.g., Connected=0, Static=1, OSPF=110).
4
Compare Metric values
Ties between identical prefix lengths from the same routing protocol are broken
Protocol-specific metrics (cost, hop count, bandwidth) determine the best path within that specific protocol.
5
Execute packet forwarding
The packet is encapsulated and sent via the designated exit interface or next-hop IP
The decision path concludes with Layer 2 rewrite and transmission.

Anahtar Kavram

Cisco Router Forwarding Decision Hierarchy (LPM -> AD -> Metric)
Soru 10Soru

Refer to the following IPv4 routing table snippet from a Cisco router:

text
Gateway of last resort is 192.168.100.1 to network 0.0.0.0

S 10.20.0.0/16 [1/0] via 192.168.1.1
D 10.20.30.0/24 [90/307200] via 192.168.23.3, GigabitEthernet0/0/2
O 10.20.30.64/27 [110/20] via 192.168.12.2, GigabitEthernet0/0/1
S* 0.0.0.0/0 [1/0] via 192.168.100.1, GigabitEthernet0/0/0

The router receives a packet with a destination IP address of 10.20.30.77. Which next-hop IP address will the router select to forward this packet?

Cevabı ve açıklamayı göster

Cevap: 192.168.12.2

Cevap

192.168.12.2
When a router receives a packet, it compares the destination IP address against the routing table entries and selects the route with the longest prefix match (most specific subnet mask). The destination IP address 10.20.30.77 falls within the subnet range 10.20.30.64 to 10.20.30.95 (/27). Among all matching routes (/16, /24, /27, and /0), /27 has the greatest number of matching network bits, making the next-hop IP address 192.168.12.2 the correct forwarding choice.

Adım Adım Çözüm

1
Identify all candidate routes that match the destination IP 10.20.30.77.
The IP address 10.20.30.77 falls into three specific route ranges: 10.20.0.0/16, 10.20.30.0/24, and 10.20.30.64/27 (range 10.20.30.64 to 10.20.30.95), plus the default route 0.0.0.0/0.
Routing decision logic requires evaluating all matching entries in the IPv4 routing table.
2
Apply the Longest Prefix Match (LPM) rule to select the route with the longest subnet mask.
Comparing the subnet mask lengths (/16, /24, and /27), the prefix /27 is the longest (most specific) match.
The router always prioritizes prefix length above Administrative Distance or Metric when choosing between matching routes.
3
Determine the next-hop IP associated with the chosen /27 route.
The route O 10.20.30.64/27 specifies next-hop IP 192.168.12.2 via GigabitEthernet0/0/1.
The forward decision routes the packet out the next hop designated by the winning route.

Anahtar Kavram

Longest Prefix Match (LPM) Precedence
Soru 11Soru

A network operations engineer is provisioning IPv6 static routing on router Edge-Rtr. The design requirements specify:
1. All default traffic must be forwarded to the primary service provider gateway at global unicast address 2001:db8:1000:1::12001:\text{db8}:1000:1::1.
2. A backup static route for internal network 2001:db8:abc:10::/642001:\text{db8}:\text{abc}:10::/64 must direct traffic to link-local next-hop address fe80::2\text{fe80}::2 across exit interface GigabitEthernet0/0/1, functioning as a floating route to back up a primary OSPFv3 route (administrative distance 110).

Which TWO Cisco IOS configuration commands correctly fulfill these requirements?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: ipv6 route ::/0 2001:db8:1000:1::1; ipv6 route 2001:db8:abc:10::/64 GigabitEthernet0/0/1 fe80::2 120

Cevap

The correct commands are 'ipv6 route ::/0 2001:db8:1000:1::1' for default routing to the global unicast address, and 'ipv6 route 2001:db8:abc:10::/64 GigabitEthernet0/0/1 fe80::2 120' for the fully-specified floating static route.
The command configuring the default prefix '::/0' to the global unicast address correctly establishes default forwarding. The command referencing prefix '2001:db8:abc:10::/64' with interface 'GigabitEthernet0/0/1', link-local address 'fe80::2', and administrative distance '120' correctly satisfies all syntax rules for link-local next hops and floating route precedence.

Adım Adım Çözüm

1
Identify the proper prefix and syntax for an IPv6 default static route.
The IPv6 default route prefix is ::/0::/0. When using a global unicast next hop, specifying an exit interface is optional.
Global unicast addresses are globally reachable and routable without explicit interface disambiguation.
2
Identify the mandatory syntax requirements when using an IPv6 link-local address as a next-hop.
Because link-local addresses (FE80::/10) are non-routable outside their local link, Cisco IOS requires specifying the local outbound exit interface along with the link-local next-hop address.
Without specifying the exit interface, the router cannot determine which local interface connects to the target link-local neighbor.
3
Evaluate the administrative distance requirement for floating static routes.
The floating static route must have an administrative distance greater than the active route protocol (OSPFv3 AD = 110), so an AD of 120 is required.
Routes with lower administrative distance values take priority in the routing table.

Anahtar Kavram

IPv6 static route configuration syntax, link-local next-hop requirements, and floating static route administrative distance manipulation.
Soru 12Soru

An administrator is reviewing the following Cisco IOS command output from router HQ-R3, which is connected to a shared Ethernet LAN segment alongside other OSPFv2 routers:

HQ-R3# show ip ospf interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 192.168.1.3/24, Area 0
Process ID 1, Router ID 10.3.3.3, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DROTHER, Priority 0
Designated Router (ID) 10.4.4.4, Interface address 192.168.1.4
Backup Designated Router (ID) 10.2.2.2, Interface address 192.168.1.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

If both the current Designated Router (10.4.4.4) and Backup Designated Router (10.2.2.2) fail simultaneously, which statement correctly describes the operational outcome for HQ-R3 during the resulting election?

Cevabı ve açıklamayı göster

Cevap: HQ-R3 will remain in the DROTHER state and is ineligible to become either the DR or BDR because its configured interface priority is zero.

Cevap

HQ-R3 will remain in the DROTHER state and is ineligible to become either the DR or BDR because its configured interface priority is zero.
In OSPFv2 broadcast multi-access networks, an interface configured with an OSPF priority of 0 (`ip ospf priority 0`) is explicitly excluded from DR/BDR elections. Regardless of failures of the current DR and BDR or the numerical value of HQ-R3's Router ID (10.3.3.3), HQ-R3 will always remain in the DROTHER state.

Adım Adım Çözüm

1
Examine the interface command output for HQ-R3.
The output indicates `Priority 0` and current state `DROTHER` on interface GigabitEthernet0/0.
Interface priority dictates eligibility and precedence in OSPF DR/BDR elections.
2
Evaluate the effect of Priority 0 on OSPF elections.
An OSPF interface priority of 0 completely disqualifies the router interface from being elected as Designated Router (DR) or Backup Designated Router (BDR).
This is a key administrative control mechanism to prevent specific routers (such as lower-capacity branch routers) from assuming DR responsibilities.
3
Determine the outcome when active DR and BDR fail.
Even if all other routers fail or have lower Router IDs, HQ-R3 will never transition out of the DROTHER state.
Priority 0 strictly overrides Router ID tie-breaking rules.

Anahtar Kavram

OSPFv2 Interface Priority 0 Election Exclusion
Soru 13Soru

A network technician is configuring high availability on interface GigabitEthernet0/1 of a Cisco IOS router. The interface is currently assigned the physical IPv4 address 192.168.10.1/24192.168.10.1/24. The technician enters the command `standby 1 ip 192.168.10.1` under interface configuration mode. Which outcome will occur as a result of executing this command?

Cevabı ve açıklamayı göster

Cevap: Cisco IOS rejects the virtual IP assignment because HSRP requires the virtual IP address to be distinct from any interface physical IP address in the group.

Cevap

Cisco IOS rejects the virtual IP assignment because HSRP requires the virtual IP address to be distinct from any interface physical IP address in the group.
In Cisco IOS HSRP implementations, the virtual IP address must be a unique IP address within the local subnet that is not configured as the physical IP address of any interface in the HSRP group. When an administrator attempts to assign an existing physical IP address as the HSRP virtual IP, Cisco IOS rejects the command with an error message.

Adım Adım Çözüm

1
Analyze the HSRP virtual IP configuration rule
HSRP (Hot Standby Router Protocol) requires an unassigned IP address within the subnet to serve as the shared virtual gateway IP.
Assigning an interface's active physical IP address as the HSRP virtual IP causes IP address conflicts and ARP resolution issues.
2
Compare HSRP behavior with VRRP behavior
While VRRP permits a router to act as the IP address owner (using its physical IP as the virtual IP with priority 255), HSRP explicitly forbids this.
Cisco IOS enforces this restriction at command entry for HSRP and generates an error message.
3
Determine the CLI command outcome
Executing `standby 1 ip 192.168.10.1` on an interface already using 192.168.10.1192.168.10.1 causes Cisco IOS to reject the command.
The system prevents invalid HSRP group configuration.

Anahtar Kavram

HSRP Virtual IP Address Assignment Restrictions vs VRRP IP Ownership
Soru 14Soru

A network administrator intends to configure a backup floating static route on router R1 to reach destination network 10.50.0.0/1610.50.0.0/16 in the event that the primary route learned via OSPF fails. The administrator enters the following configuration command on R1:

`ip route 10.50.0.0 255.255.0.0 192.168.12.2 105`

What is the immediate impact of this configuration on router R1's routing table?

Cevabı ve açıklamayı göster

Cevap: The static route becomes the active route in the routing table because its administrative distance of 105 is lower than OSPF's default administrative distance of 110.

Cevap

The static route becomes the active route in the routing table because its administrative distance of 105 is lower than OSPF's default administrative distance of 110.
In Cisco IOS, administrative distance (AD) determines which routing source is preferred when multiple sources provide routes to the same network prefix. OSPF has a default AD of 110. Because the configured static route specifies an AD of 105, which is lower (more trusted) than 110, the static route immediately takes precedence and replaces the OSPF route in the active routing table.

Adım Adım Çözüm

1
Identify default Administrative Distance (AD) values
Default OSPF AD is 110; default Static Route AD is 1.
Administrative distance measures the trustworthiness of a routing information source.
2
Analyze the configured static route parameter
The trailing value `105` in `ip route 10.50.0.0 255.255.0.0 192.168.12.2 105` sets the static route's AD to 105.
Floating static routes require an AD value higher than the primary routing protocol to stay hidden until the primary path fails.
3
Compare AD values to determine routing table selection
105 (configured static) < 110 (OSPF), so the static route is selected and immediately replaces the OSPF route.
When multiple routes to the exact same destination prefix exist, the router installs the route with the lowest administrative distance into the routing table.

Anahtar Kavram

Floating Static Route Administrative Distance Selection
Soru 15Soru

Router R1 learns routes to the remote destination subnet 172.16.50.0/24172.16.50.0/24 via OSPF, which operates with a administrative distance of 110. A network administrator wants to manually configure a backup floating static route toward 172.16.50.0/24172.16.50.0/24 using next-hop IP address 192.168.12.2192.168.12.2. This backup route must remain inactive in the routing table unless the primary OSPF route fails. Which command must be configured on router R1?

Cevabı ve açıklamayı göster

Cevap: ip route 172.16.50.0 255.255.255.0 192.168.12.2 120

Cevap

The command 'ip route 172.16.50.0 255.255.255.0 192.168.12.2 120' correctly configures the floating static route with an administrative distance higher than OSPF.
A floating static route requires an Administrative Distance higher than that of the primary routing protocol. Since OSPF has an AD of 110, setting the static route AD to 120 ensures it will only be installed in the routing table if the OSPF route disappears.

Adım Adım Çözüm

1
Identify the primary dynamic routing protocol and its administrative distance (AD).
OSPF is the primary routing protocol with an AD of 110.
Floating static routes rely on Administrative Distance ranking to remain inactive until primary routes fail.
2
Determine the required AD for the floating static backup route.
The AD of the static route must be configured to a value strictly greater than 110 (such as 120).
Cisco IOS router forwarding logic installs routes with lower AD values into the IP routing table first.
3
Validate Cisco IOS static route syntax including destination, mask, next-hop IP, and AD.
'ip route 172.16.50.0 255.255.255.0 192.168.12.2 120' fulfills all parameters accurately.
The AD parameter is appended at the end of the 'ip route' command string.

Anahtar Kavram

Floating Static Route Administrative Distance Configuration
Soru 16Soru

A network administrator is configuring IPv4 static routing on router R1. Router R1 currently learns the primary route to destination network 192.168.50.0/24192.168.50.0/24 via iBGP, which has an Administrative Distance of 200. The administrator must configure two static routes:
1. A standard static route to reach network 10.100.1.0/2410.100.1.0/24 via next-hop IPv4 address 172.16.1.2172.16.1.2.
2. A backup floating static route to reach network 192.168.50.0/24192.168.50.0/24 via next-hop IPv4 address 172.16.1.2172.16.1.2 that remains inactive until the primary iBGP route fails.

Which two `ip route` commands must the administrator configure on router R1?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: ip route 10.100.1.0 255.255.255.0 172.16.1.2; ip route 192.168.50.0 255.255.255.0 172.16.1.2 210

Cevap

The commands 'ip route 10.100.1.0 255.255.255.0 172.16.1.2' and 'ip route 192.168.50.0 255.255.255.0 172.16.1.2 210' are correct.
The command 'ip route 10.100.1.0 255.255.255.0 172.16.1.2' is correct because it follows standard IPv4 static route syntax to direct traffic destined for network 10.100.1.0/24 to next-hop address 172.16.1.2. The command 'ip route 192.168.50.0 255.255.255.0 172.16.1.2 210' is correct because a floating static route requires an Administrative Distance higher than the primary route (iBGP AD = 200); setting the AD to 210 ensures it remains inactive until the primary route fails.

Adım Adım Çözüm

1
Identify standard Cisco IOS static route syntax for network 10.100.1.0/24
ip route 10.100.1.0 255.255.255.0 172.16.1.2
Standard IPv4 static routes use the syntax 'ip route <destination-prefix> <subnet-mask> <next-hop-ip>' with a default Administrative Distance of 1.
2
Determine Administrative Distance requirement for the backup floating static route
Target Administrative Distance must be > 200
A floating static route acts as a backup only when its Administrative Distance is configured higher than the primary path's routing protocol (iBGP AD = 200).
3
Select the correct floating static route command
ip route 192.168.50.0 255.255.255.0 172.16.1.2 210
Specifying an Administrative Distance of 210 ensures the static route remains out of the routing table until the iBGP route (AD 200) is lost.

Anahtar Kavram

IPv4 Static Route Syntax and Floating Static Route Administrative Distance Selection
Soru 17Soru

A router receives its primary path to the 172.20.0.0/16 subnet via internal EIGRP. Which administrative distance value should be configured on a static route to ensure it functions as an inactive floating backup route until the primary path fails?

Cevabı ve açıklamayı göster

Cevap: 95

Cevap

An administrative distance value of 95 should be specified for the static route.
A floating static route is designed to serve as a backup path that only installs into the IP routing table when the primary route fails. Router forwarding decisions prioritize routes with lower administrative distance (AD) values. Internal EIGRP has a default AD of 90. Assigning a value of 95 ensures the static route has a higher AD than the primary EIGRP route, keeping it dormant until EIGRP route failure occurs.

Adım Adım Çözüm

1
Identify the administrative distance of the primary routing protocol.
Internal EIGRP has a default administrative distance (AD) of 90.
Routers use administrative distance to evaluate trustworthiness when selecting the best path among different routing sources.
2
Determine the required administrative distance for a floating static backup route.
The backup static route must have an AD greater than 90 (e.g., 95).
A floating static route remains inactive in the routing table only if its administrative distance is higher than that of the active primary routing protocol.

Anahtar Kavram

Floating Static Route Administrative Distance
Tahmini Süre:45s
Soru 18Soru

A network administrator is reviewing IPv4 static route syntax and operational characteristics on a Cisco IOS router. Which two statements regarding Cisco IPv4 static routing are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: A static route configured with an administrative distance higher than a primary dynamic routing protocol serves as a floating static backup route.; Cisco IOS static route syntax requires specifying the destination network mask using dotted-decimal format rather than a wildcard mask.

Cevap

The correct statements are that configuring an administrative distance higher than the primary protocol creates a floating backup route, and that Cisco IOS static routes require dotted-decimal subnet masks.
Configuring a static route with an administrative distance higher than the primary routing protocol creates a floating static route that remains inactive until the primary route fails. Additionally, Cisco IOS 'ip route' command syntax strictly requires dotted-decimal subnet masks for prefix specification.

Adım Adım Çözüm

1
Analyze static route administrative distance mechanics for floating routes.
Lower administrative distance values are preferred in the routing table. To create a backup (floating) route, its administrative distance must be set higher than the primary route source.
If set lower than the primary dynamic protocol (e.g., 90 vs 110 for OSPF), the static route will preempt the primary protocol immediately.
2
Verify Cisco IOS CLI command syntax parameters for static routing.
The correct command format is 'ip route <destination-prefix> <subnet-mask> {next-hop-ip | exit-interface} [distance]'.
Subnet masks in static routes use dotted-decimal format (e.g., 255.255.255.0), and next-hop IP addresses must belong to the neighboring router.

Anahtar Kavram

Cisco IPv4 Static Route Syntax and Floating Static Administrative Distance Calibration
Tahmini Süre:1m 0s
Soru 19Soru

A Cisco router receives an IPv4 packet destined for a remote network. Place the router forwarding decision and packet processing steps in the correct chronological order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct order of router forwarding decision logic begins with inspecting the destination IP header, evaluating the routing table using Longest Prefix Match, resolving equal prefix length ties using Administrative Distance and metric, identifying the next-hop IP and exit interface, and performing Layer 2 header rewriting along with TTL decrement prior to frame transmission.
Router forwarding logic follows a deterministic sequence: packet IP inspection -> Longest Prefix Match evaluation -> Administrative Distance/metric tie-breaking for equal prefixes -> next-hop and exit interface resolution -> Layer 2 MAC resolution, TTL decrement, and frame forwarding.

Adım Adım Çözüm

1
Examine packet header
Destination IPv4 address is extracted from the incoming packet.
The router requires the destination address to initiate a routing table lookup.
2
Apply Longest Prefix Match rule
The routing table entry with the longest subnet mask matching the destination IP is chosen.
LPM is the primary criterion in Cisco IPv4 forwarding decision logic.
3
Compare Administrative Distance and metric
Ties between identical prefix lengths from different routing sources are resolved.
Administrative Distance ranks route trustworthiness when prefix lengths are equal.
4
Retrieve egress forwarding details
The next-hop IPv4 address and outbound interface are identified.
Forwarding requires knowing where to encapsulate and send the packet next.
5
Execute Layer 2 rewrite and transmission
TTL is decremented by 1, IP header checksum updated, next-hop MAC resolved via ARP, and frame sent.
Layer 2 encapsulation is link-local and must be rewritten for each hop along the path.

Anahtar Kavram

Router Forwarding Decision Logic
Soru 20Soru

A network administrator needs to configure a static route on router R1 to reach the destination subnet 2001:db8:fed:10::/642001:\text{db8}:\text{fed}:10::/64. The next-hop router's interface uses the link-local IPv6 address fe80::2\text{fe80}::2 across the local GigabitEthernet0/0/1 point-to-point link. Which command must be entered on R1 to properly establish this route?

Cevabı ve açıklamayı göster

Cevap: ipv6 route 2001:db8:fed:10::/64 GigabitEthernet0/0/1 fe80::2

Cevap

The command 'ipv6 route 2001:db8:fed:10::/64 GigabitEthernet0/0/1 fe80::2' is the correct configuration.
When configuring an IPv6 static route using a link-local address as the next hop, Cisco IOS requires a fully specified route syntax containing both the local exit interface and the link-local address in the format: 'ipv6 route <prefix/mask> <exit-interface> <link-local-address>'. The option specifying 'GigabitEthernet0/0/1' followed by 'fe80::2' accurately matches this syntax requirement.

Adım Adım Çözüm

1
Identify the target destination prefix and prefix length
Destination prefix is 2001:db8:fed:10::/642001:\text{db8}:\text{fed}:10::/64.
Static routing commands start with the target network prefix and mask length.
2
Evaluate the next-hop address type
The next-hop address fe80::2\text{fe80}::2 is a link-local IPv6 address (FE80::/10 range).
Link-local addresses are non-routable and scoped strictly to a single link segment.
3
Apply Cisco IOS fully specified IPv6 static route syntax rules
The required command format is 'ipv6 route <prefix/mask> <exit-interface> <link-local-next-hop>'.
Specifying the exit interface GigabitEthernet0/0/1 before the link-local address fe80::2\text{fe80}::2 resolves interface ambiguity.

Anahtar Kavram

Fully specified IPv6 static routes with link-local next-hop addresses
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