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1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 561Soru →

A network engineer is configuring an IPv4 static route on router R1 to reach destination network 172.20.40.0/24172.20.40.0/24. The path connects through an Ethernet broadcast multi-access interface (GigabitEthernet0/1) to the next-hop router address 10.0.12.210.0.12.2. Which command configures a fully specified static route that prevents recursive lookup overhead while avoiding excessive Address Resolution Protocol (ARP) table expansion on the multi-access segment?

Cevabı ve açıklamayı göster

Cevap: ip route 172.20.40.0 255.255.255.0 GigabitEthernet0/1 10.0.12.2

Cevap

The command 'ip route 172.20.40.0 255.255.255.0 GigabitEthernet0/1 10.0.12.2' correctly configures a fully specified static route.
The correct command uses the syntax 'ip route 172.20.40.0 255.255.255.0 GigabitEthernet0/1 10.0.12.2'. By providing both the local exit interface and the specific next-hop IPv4 address, the router creates a fully specified route. This prevents recursive table lookup overhead (associated with next-hop IP only) and avoids excessive ARP requests for individual destination IPs (associated with exit interface only on multi-access media).

Adım Adım Çözüm

1
Identify the static route requirement for a broadcast multi-access network (Ethernet).
On Ethernet links, specifying only an exit interface causes the router to treat all destination IP addresses as directly connected, issuing ARP requests for every destination host.
Ethernet is a multi-access network requiring Layer 2 MAC address resolution.
2
Evaluate the difference between directly attached, next-hop, and fully specified static routes.
A fully specified static route includes both the local exit interface (GigabitEthernet0/1) and the next-hop IP address (10.0.12.2).
This eliminates the need for recursive routing lookups while pinpointing the exact Layer 2 next-hop neighbor.
3
Verify Cisco IOS syntax ordering and subnet mask formatting.
The correct syntax order is 'ip route <prefix> <mask> <exit-interface> <next-hop-ip>'.
Dotted-decimal subnet masks must be used instead of wildcard masks.

Anahtar Kavram

Fully Specified IPv4 Static Route Syntax on Multi-access Networks
Tahmini Süre:1m 15s
Soru 562Soru →

A network administrator configures OSPFv2 across four Cisco routers connected to a single Ethernet switch on a broadcast multiaccess segment. After allowing time for network convergence, the administrator issues the `show ip ospf neighbor` command on Router R3, which is neither the Designated Router (DR) nor the Backup Designated Router (BDR). The output shows that the neighbor relationship with Router R4 (also a DROther) is in the `2WAY/DROTHER` state. Which statement correctly describes this scenario?

Cevabı ve açıklamayı göster

Cevap: This is normal expected behavior because non-DR/BDR routers on a broadcast network form bi-directional communication but do not proceed to full database synchronization with each other.

Cevap

This is normal expected behavior because non-DR/BDR routers on a broadcast network form bi-directional communication but do not proceed to full database synchronization with each other.
On broadcast multiaccess networks (such as Ethernet), OSPF elects a Designated Router (DR) and Backup Designated Router (BDR). All other routers on the segment are designated as DROthers. To minimize routing overhead and redundant LSA exchanges, DROthers only establish FULL adjacencies with the DR and BDR. Between two DROther routers, bi-directional communication is established and maintained at the 2-WAY state, which is normal and expected behavior.

Adım Adım Çözüm

1
Analyze the network topology and router roles
The network is a broadcast multiaccess Ethernet segment with four OSPFv2 routers. R3 and R4 are identified as DROther routers (neither DR nor BDR).
OSPF behaves differently on broadcast networks depending on whether the routers involved are DR/BDR or DROthers.
2
Evaluate the OSPF neighbor state machine logic for DROther to DROther communications
DROther routers achieve 2-WAY state with one another once bi-directional Hello exchange succeeds.
To prevent redundant LSA exchanges and conserve network resources on multiaccess media, full database synchronization (FULL state) only occurs between DROthers and the DR/BDR.
3
Determine if troubleshooting is required for the 2WAY/DROTHER status
No troubleshooting is needed; the neighbor state is operating normally as designed by OSPF standards.
Reaching 2-WAY state confirms correct matching of Area ID, subnet mask, authentication, MTU handling, and Hello/Dead timers.

Anahtar Kavram

OSPF DR/BDR neighbor adjacency states on broadcast networks
Soru 563Soru →

A network administrator configures a static route using only a next-hop IP address. Place the operational steps in the correct order that a Cisco IOS router performs to process and forward a packet using this recursive static route.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence of packet forwarding steps for a recursive static route is: 1) Evaluate destination against routing table for longest prefix match, 2) Identify matching static route and extract next-hop IP, 3) Perform recursive lookup to resolve next-hop IP to an exit interface, 4) Query ARP table for next-hop MAC address on that interface, 5) Encapsulate frame and forward out the exit interface.
When an IPv4 static route is configured using only a next-hop IP address, Cisco IOS must resolve the outgoing interface by performing a second (recursive) lookup in the routing table. First, the router matches the packet destination address to the static route entry. Second, it extracts the next-hop IP. Third, it recursively resolves that next-hop IP to a connected interface. Fourth, it uses ARP on that interface to determine the next-hop MAC address. Finally, it encapsulates the packet and forwards it out the interface.

Adım Adım Çözüm

1
Examine incoming packet destination
Longest match matching the static route prefix is found
Cisco IOS routing logic always evaluates the destination IPv4 address against all known routes using longest prefix matching first.
2
Extract next-hop IP address
Next-hop IPv4 address identified
Static routes configured in the format 'ip route prefix mask next-hop-ip' do not explicitly define the outgoing interface.
3
Perform recursive routing lookup
Exit interface and directly connected network identified
The router must locate a connected or dynamic route entry that covers the next-hop IP address to find the exit interface.
4
Resolve Layer 2 address
Next-hop MAC address obtained from ARP cache
For multi-access Ethernet interfaces, the router requires the destination MAC address of the next-hop gateway.
5
Frame encapsulation and transmission
Packet successfully transmitted
The packet is encapsulated with the local exit interface source MAC and next-hop destination MAC address.

Anahtar Kavram

Recursive Static Route Lookup and Packet Forwarding Process
Soru 564Soru →

A Cisco router initializes OSPFv2 process 100 with no explicitly configured router ID and no active loopback interfaces. The router has three physical interfaces configured with the following IPv4 addresses and operational states:

- GigabitEthernet0/0: 10.200.15.1/24 (Status: up, Line Protocol: up)
- GigabitEthernet0/1: 172.25.1.254/16 (Status: up, Line Protocol: up)
- GigabitEthernet0/2: 192.168.50.5/30 (Status: up, Line Protocol: down)

Which IPv4 address will OSPFv2 select as the Router ID when the routing process starts?

Cevabı ve açıklamayı göster

Cevap: 172.25.1.254; 172.25.1.254/16

Cevap

172.25.1.254
When OSPF process initializes without an explicit 'router-id' command or any active loopback interfaces, it chooses the highest IPv4 address among operationally active (up/up) physical interfaces. Since GigabitEthernet0/2 is inactive (up/down), only GigabitEthernet0/0 (10.200.15.1) and GigabitEthernet0/1 (172.25.1.254) are eligible. 172.25.1.254 is the highest active address.

Adım Adım Çözüm

1
Evaluate the OSPF Router ID election precedence rules
OSPF selects the router ID using the following priority: 1) Manually configured 'router-id' command, 2) Highest IPv4 address of any active loopback interface, 3) Highest IPv4 address of any active non-loopback physical interface.
Since no manual router ID or loopback interface exists, the selection defaults to active physical interfaces.
2
Filter interfaces by operational status
GigabitEthernet0/0 (10.200.15.1) and GigabitEthernet0/1 (172.25.1.254) are both up/up (active). GigabitEthernet0/2 (192.168.50.5) is up/down (inactive) and is disqualified from router ID selection.
OSPF only considers interfaces whose line protocol is operationally active (up/up).
3
Determine the highest active IPv4 address
Compare active addresses 10.200.15.1 and 172.25.1.254. 172.25.1.254 is numerically higher.
Numeric comparison of active physical interface IPv4 addresses yields 172.25.1.254 as the highest value.

Anahtar Kavram

OSPFv2 Router ID election logic prioritizes active loopback interfaces over physical interfaces, selecting the highest IPv4 address among operationally active (up/up) interfaces when no manual router ID is specified.
Soru 565Soru →

An engineer inspects the OSPFv2 operational status of interface GigabitEthernet0/0 on router R1 using the `show ip ospf interface` command:

text
GigabitEthernet0/0 is up, line protocol is up
Internet Address 192.168.1.10/24, Area 0
Process ID 1, Router ID 192.168.1.10, Network Type BROADCAST, Cost: 1
State DROTHER, Priority 0
Designated Router (ID) 10.3.3.3, Interface address 192.168.1.3
Backup Designated Router (ID) 10.2.2.2, Interface address 192.168.1.2

If the active Designated Router (10.3.3.3) reboots and leaves the network, which role will router R1 assume?

Cevabı ve açıklamayı göster

Cevap: R1 will remain in the DROTHER state and will not participate in the election for Designated Router or Backup Designated Router.

Cevap

Router R1 will remain in the DROTHER state and will not participate in the election for Designated Router or Backup Designated Router.
In OSPFv2 broadcast multiaccess networks, setting an interface priority to 0 completely disables DR/BDR election eligibility for that interface. Even if the current DR fails and a new election occurs, any router with a priority of 0 remains strictly in the DROTHER state.

Adım Adım Çözüm

1
Analyze the output of the 'show ip ospf interface' command for router R1.
Interface GigabitEthernet0/0 has an OSPF priority set to 0 ('Priority 0').
OSPF interface priority determines eligibility for DR and BDR roles during elections on multiaccess networks.
2
Apply OSPF DR/BDR election rules regarding priority values.
A router interface configured with an OSPF priority of 0 (ip ospf priority 0) is ineligible to become a DR or BDR.
Setting priority to 0 forces the router interface to remain in the DROTHER state indefinitely regardless of router ID, IP address, or failures of existing DR/BDR routers.
3
Determine the outcome when the active DR fails.
The current BDR (10.2.2.2) promotes to DR, and R1 remains a DROTHER, taking no part in any subsequent BDR election.
R1 is excluded from all DR/BDR election calculations due to its priority of 0.

Anahtar Kavram

OSPF Priority 0 Exclusion from DR/BDR Selection
Soru 566Soru →

A Cisco router relies on OSPF (administrative distance 110) to reach destination network 192.168.10.0/24192.168.10.0/24. A backup path is connected via next-hop IPv4 address 10.0.0.210.0.0.2. The network engineer must configure a floating static route so that traffic uses this secondary link only when the primary OSPF path becomes unavailable. Which command correctly configures this backup static route?

Cevabı ve açıklamayı göster

Cevap: ip route 192.168.10.0 255.255.255.0 10.0.0.2 120

Cevap

The command 'ip route 192.168.10.0 255.255.255.0 10.0.0.2 120' correctly configures the floating static route.
The command specifying 'ip route 192.168.10.0 255.255.255.0 10.0.0.2 120' uses proper Cisco IOS syntax with a subnet mask and assigns an administrative distance of 120. Because 120 is higher than OSPF's administrative distance of 110, the route will stay out of the routing table until the OSPF route is lost.

Adım Adım Çözüm

1
Identify the primary routing protocol's Administrative Distance (AD)
OSPF has an AD of 110.
Floating static routes must have an AD strictly higher than the primary routing protocol to remain inactive while the primary route is present in the routing table.
2
Verify Cisco IOS static route command syntax
Syntax: 'ip route <destination-network> <subnet-mask> <next-hop-ip> [distance]'.
Cisco static routes require a dotted-decimal subnet mask (e.g., 255.255.255.0) rather than a wildcard mask.
3
Select the correct Administrative Distance value
An AD of 120 is greater than 110.
Setting the AD to 120 ensures the static route remains floating in backup state until the primary OSPF route (AD 110) fails.

Anahtar Kavram

Floating Static Route Administrative Distance
Tahmini Süre:1m 15s
Soru 567Soru →

Match each OSPFv2 interface configuration command or operational trait on the left with its corresponding network type property or election behavior on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Interface command `ip ospf priority 0` applied on an Ethernet interface
Interface command `ip ospf network point-to-point` applied on a multi-access Ethernet link
Default broadcast network type operation on an Ethernet interface
Final tie-breaker when OSPF router priorities are equal on a shared segment

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

The interface priority 0 command forces DROTHER state and excludes the router from elections; point-to-point network type on Ethernet suppresses DR/BDR election while using 10s/40s timers; broadcast network type enables DR/BDR election with 10s/40s timers; and equal priority elections break ties using the highest Router ID.
Each item matches its corresponding operational trait: priority 0 forces DROTHER status and excludes the interface from elections; configuring point-to-point on Ethernet suppresses DR/BDR election while using default 10s/40s timers; broadcast networks elect DR/BDR with 10s/40s timers; and equal priority ties are broken by the highest Router ID.

Adım Adım Çözüm

1
Analyze OSPF priority 0 behavior
Interface priority 0 prevents a router from ever becoming a Designated Router or Backup Designated Router.
An interface priority of 0 explicitly removes the router from DR/BDR candidate status on multi-access networks.
2
Analyze point-to-point network type behavior on Ethernet media
Modifying network type to point-to-point bypasses DR/BDR election while maintaining standard 10s/40s timers.
Point-to-point connections assume only two routers exist, making DR/BDR election redundant.
3
Analyze default broadcast interface behavior
Broadcast networks elect DR/BDR neighbors and use Hello/Dead timers of 10 seconds and 40 seconds.
Broadcast multi-access links require a DR/BDR to limit adjacency formation across shared media.
4
Identify the election tie-breaker rule
The highest Router ID breaks priority ties among DR candidates.
OSPF DR election precedence evaluates priority first; if priorities match, the highest Router ID wins.

Anahtar Kavram

OSPFv2 Network Types and DR/BDR Election Mechanics
Soru 568Soru →

Router R1 and Router R2 are directly connected via their GigabitEthernet0/0 interfaces. An administrator configures OSPFv2 on both interfaces in Area 0. On R1, GigabitEthernet0/0 uses default OSPF timers (Hello 10 seconds, Dead 40 seconds). On R2, the Hello timer is manually set to 15 seconds and the Dead timer to 60 seconds. What will be the outcome of this OSPFv2 configuration between R1 and R2?

Cevabı ve açıklamayı göster

Cevap: The routers will fail to establish an OSPF neighbor relationship because Hello and Dead timers must match exactly.

Cevap

The routers will fail to establish an OSPF neighbor relationship because Hello and Dead timers must match exactly.
For two OSPFv2 routers to form a neighbor relationship, key parameters in their Hello packets must match exactly. These include Area ID, Subnet Mask, Hello Interval, Dead Interval, Authentication settings, and Option flags. Because R1 has timers set to 10s/40s and R2 has timers set to 15s/60s, neither router will process the other's Hello packets as valid, preventing any neighbor relationship from forming.

Adım Adım Çözüm

1
Identify the OSPF Hello packet parameters required for neighbor discovery.
Mandatory matching fields include Area ID, Subnet Mask, Hello/Dead intervals, Authentication, and Stub flag.
When a router receives an OSPF Hello packet, it compares these fields against its local interface parameters.
2
Compare the configured timer values on R1 and R2.
R1 uses Hello 10s / Dead 40s, while R2 uses Hello 15s / Dead 60s.
Because the values do not match, both routers silently drop the incoming Hello packets from each other.
3
Determine the final neighbor state.
No neighbor relationship is established.
Without matching parameters in Hello packets, routers cannot progress to the INIT or 2-WAY neighbor state.

Anahtar Kavram

OSPFv2 Mandatory Hello Packet Matching Parameters
Soru 569Soru →

A network engineer deploys Dynamic ARP Inspection (DAI) and DHCP Snooping on VLAN 30 of a Cisco Catalyst switch. A workstation connected to an untrusted access port is configured with a static IPv4 address rather than obtaining one via DHCP. When the workstation attempts to communicate with the default gateway, all of its traffic is dropped at the switch port. Which command sequence should be configured on the switch to permit ARP traffic from this statically configured host while maintaining DAI protection?

Cevabı ve açıklamayı göster

Cevap: Define an ARP access list matching the static IP and MAC address, then apply it using the command ip arp inspection filter <ACL_NAME> vlan 30.

Cevap

Define an ARP access list matching the static IP and MAC address, then apply it using the command ip arp inspection filter <ACL_NAME> vlan 30.
Dynamic ARP Inspection (DAI) intercept and validates all ARP requests and responses on untrusted ports against the DHCP snooping binding database. For hosts configured with static IP addresses, no entry exists in the DHCP binding database, causing DAI to drop their ARP packets. To permit static hosts while keeping DAI active, administrators must create an ARP access list defining the static IP-to-MAC pair and apply it globally to the VLAN using the command 'ip arp inspection filter <ACL_NAME> vlan <VLAN_ID>'.

Adım Adım Çözüm

1
Identify why traffic from the statically addressed host is being dropped.
DAI drops ARP packets received on untrusted ports if the IP-to-MAC mapping is absent from the DHCP snooping binding database.
Statically configured hosts do not participate in DHCP exchanges, so they lack entries in the DHCP snooping table.
2
Determine the Cisco IOS mechanism to manually permit static IP-to-MAC bindings in DAI.
An ARP Access Control List (ARP ACL) must be created containing the host's static IP and MAC address.
ARP ACLs provide a static fallback validation mechanism for DAI.
3
Apply the ARP ACL to the target VLAN.
Executing 'ip arp inspection filter <ACL_NAME> vlan 30' binds the ARP ACL to VLAN 30.
This instructs DAI to check incoming ARP packets against the static ARP ACL before consulting the DHCP binding database.

Anahtar Kavram

DAI Static ARP ACL Integration
Tahmini Süre:1m 30s
Soru 570Soru →

A network engineer is configuring router R1 to maintain redundant connectivity to an upstream ISP. R1 currently learns a default route (0.0.0.0/00.0.0.0/0) via OSPF, which has a default Administrative Distance of 110. The engineer needs to configure a floating static default route using the next-hop IP address 192.168.12.2192.168.12.2 over a secondary link so that it serves strictly as a backup if the OSPF path fails. Which TWO of the following statements accurately describe the configuration or operational behavior of this floating static route?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The command `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` correctly configures the floating static route with an administrative distance higher than OSPF.; The configured floating static route remains in the running configuration but is excluded from the IPv4 routing table while the OSPF default route is active.

Cevap

The correct statements are that `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` correctly configures the floating static route, and that the floating static route remains in the running configuration but is excluded from the active IPv4 routing table as long as the primary OSPF default route is active.
A floating static route acts as a backup path and must be configured with an Administrative Distance higher than the primary route protocol (OSPF AD 110). Using `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` properly assigns an AD of 120. Because Cisco IOS installs only the path with the lowest AD into the routing table, the static route is held in the running configuration and only populated into the IPv4 routing table if the OSPF default route is removed.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary dynamic routing protocol
OSPF has a default AD of 110.
Floating static routes rely on having a higher AD than the primary routing method so they are not chosen while the primary route is functional.
2
Evaluate the required static route syntax and AD parameter
The command `ip route 0.0.0.0 0.0.0.0 192.168.12.2 120` specifies an AD of 120, which is higher than 110.
Setting the AD to 120 satisfies the floating static route requirement.
3
Determine Cisco IOS routing table insertion rules for floating routes
The static route with AD 120 is stored in configuration but withheld from the routing table while the lower AD OSPF route (AD 110) exists.
The Cisco IOS RIB only installs the route with the lowest AD for a given destination prefix.

Anahtar Kavram

Floating Static Routes and Administrative Distance
Soru 571Soru →

A network engineer is configuring OSPFv2 on a broadcast multiaccess Ethernet network segment connecting two Cisco routers. Which two parameters must match between the connected router interfaces for an OSPFv2 neighbor adjacency to form successfully? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: OSPF Area ID; OSPF Hello and Dead timer intervals

Cevap

The parameters that must match between neighboring routers for an OSPFv2 adjacency to form are the OSPF Area ID and the OSPF Hello and Dead timer intervals.
For two routers to establish an OSPFv2 neighbor adjacency on a broadcast segment, several parameters in the OSPF Hello packets must match, including the Area ID, IPv4 subnet mask, Hello/Dead timer intervals, and authentication type/key.

Adım Adım Çözüm

1
Identify mandatory matching parameters contained in OSPF Hello packets
OSPF neighbor adjacencies require matching Area ID, Subnet Mask, Hello and Dead Timers, and Authentication fields.
A mismatch in any of these Hello packet fields prevents routers from progressing past the Init neighbor state.
2
Evaluate non-matching and unique OSPF configuration parameters
OSPF Process ID is locally significant, while OSPF Router ID must be globally unique across the autonomous system.
Process IDs are not communicated across neighbor links, and duplicate Router IDs cause database synchronization failures.

Anahtar Kavram

OSPFv2 Neighbor Adjacency Requirements
Soru 572Soru →

A network router is configured with the global configuration command `ntp master 6`. Additionally, the router has a configured association using `ntp server 172.16.40.10`. The remote NTP server at IP address 172.16.40.10172.16.40.10 is reachable and currently operates at Stratum 3. Assuming time synchronization between the router and the remote server succeeds, what stratum level will this router advertise to its downstream NTP clients?

Cevabı ve açıklamayı göster

Cevap: Stratum 4

Cevap

The router will operate at and advertise Stratum 4 because it adds 1 to the stratum level of its active upstream reference source (Stratum 3).
In Network Time Protocol (NTP), stratum levels represent the distance from an authoritative reference clock (Stratum 0). When a router synchronizes with an NTP server at Stratum NN, the router's calculated stratum level becomes N+1N + 1. Since the upstream server is at Stratum 3, the router synchronizes to it and operates at Stratum 4. The `ntp master [stratum]` command configures the router as a master NTP server using its own internal clock only if external NTP sources fail or are unreachable.

Adım Adım Çözüm

1
Determine the active NTP source
The router has an active, reachable NTP server at 172.16.40.10 operating at Stratum 3.
An active external NTP server association takes precedence over the internal `ntp master` fallback command.
2
Calculate the local router's stratum level
Stratum level = Upstream Stratum + 1 = 3 + 1 = 4.
NTP stratum levels increment by 1 for each hop away from the authoritative reference clock (Stratum 0).

Anahtar Kavram

NTP Stratum Calculation and Fallback Master Precedence
Soru 573Soru →

An engineer inspects the OSPFv2 neighbor status on router R1, which is connected to a shared Ethernet segment alongside routers R2, R3, and R4. The command output on R1 displays the following neighbor table:

text
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/DR 00:00:33 192.168.1.2 GigabitEthernet0/0
3.3.3.3 1 FULL/BDR 00:00:36 192.168.1.3 GigabitEthernet0/0
4.4.4.4 255 FULL/DROTHER 00:00:31 192.168.1.4 GigabitEthernet0/0

The administrator wants R4 (Router ID 4.4.4.4) to become the Designated Router (DR) on this network segment without changing any interface priorities. Which action will force a new DR election across the segment?

Cevabı ve açıklamayı göster

Cevap: Execute the clear ip ospf process command on all routers on the multiaccess segment.

Cevap

Execute the clear ip ospf process command on all routers on the multiaccess segment.
The correct answer identifies that OSPFv2 DR/BDR elections are non-preemptive. Once a DR and BDR are elected on a multiaccess broadcast network, a newly added router with a higher interface priority (such as R4 with priority 255) will remain in the DROTHER state. To force a new election where R4 can claim the DR role based on its priority, the OSPF adjacencies across the segment must be restarted using the `clear ip ospf process` command.

Adım Adım Çözüm

1
Analyze the current DR/BDR operational roles and OSPF priorities from the output snippet.
R2 (priority 1) is currently the active DR, R3 (priority 1) is the BDR, and R4 (priority 255) is in the DROTHER state.
R4 likely joined the segment after R2 and R3 had already established DR and BDR roles.
2
Evaluate OSPFv2 preemption behavior.
OSPF DR/BDR elections are non-preemptive. Even though R4 has a higher interface priority (255>1255 > 1), it will not displace an active DR or BDR while their OSPF processes remain operational.
Non-preemption prevents network instability and frequent routing table recalculations.
3
Determine the necessary operational command to trigger a fresh election.
Executing `clear ip ospf process` forces all routers on the broadcast domain to reset their OSPF adjacencies and conduct a new DR/BDR election.
During a new election with all routers participating simultaneously, R4 will win the DR role because it has the highest configured interface priority.

Anahtar Kavram

OSPFv2 DR/BDR elections on broadcast multiaccess networks are non-preemptive; active DR/BDR roles persist until adjacencies are reset or the active DR/BDR interfaces go down.
Soru 574Soru →

A border router receives a primary IPv4 route for destination network 198.51.100.0/24198.51.100.0/24 via external BGP (eBGP), which has an administrative distance of 2020. The network engineer must configure a backup floating static route via next-hop IPv4 address 203.0.113.5203.0.113.5 that remains inactive in the routing table unless the primary eBGP path becomes unavailable. Which command must be configured on the border router to achieve this requirement?

Cevabı ve açıklamayı göster

Cevap: ip route 198.51.100.0 255.255.255.0 203.0.113.5 25

Cevap

The command `ip route 198.51.100.0 255.255.255.0 203.0.113.5 25` correctly configures the backup floating static route.
To configure a floating static route as a backup to an eBGP-learned route (which has a default administrative distance of 2020), the static route must be assigned an administrative distance strictly greater than 2020. Setting the distance to 2525 ensures that Cisco IOS places the static route into the routing table only when the eBGP route is withdrawn. Additionally, Cisco IOS static route configuration requires a dotted-decimal subnet mask rather than a wildcard mask.

Adım Adım Çözüm

1
Identify the administrative distance of the primary route protocol.
The primary route is learned via eBGP, which has a default administrative distance of 2020.
Cisco IOS selects routes with the lowest administrative distance for placement in the routing table.
2
Determine the required administrative distance for the backup route.
The administrative distance must be set to a value strictly greater than 2020 (such as 2525).
A higher administrative distance keeps the static route floating (inactive) in the background until the primary eBGP path drops.
3
Verify Cisco IOS IPv4 static route syntax requirements.
The syntax is `ip route <network-prefix> <subnet-mask> <next-hop-ip> [administrative-distance]`.
The command requires a standard subnet mask rather than an OSPF/ACL wildcard mask.

Anahtar Kavram

Floating Static Route Administrative Distance Configuration
Tahmini Süre:1m 30s
Soru 575Soru →

A network administrator configures a Cisco IOS router to synchronize its time with an upstream NTP server operating at Stratum 2. Arrange the following steps in the correct chronological order from the initial synchronization attempt to successful time synchronization on the router.

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Cevap

The correct sequence starts with transmitting the NTP request packet (UDP 123), followed by receiving the server response with Stratum 2 details, calculating offset and delay, updating the local clock to Stratum 3, and finally marking the peer association as synchronized (∗*).
The NTP synchronization process must follow a logical operational sequence: first, sending a client poll via UDP port 123; second, receiving the server's timestamp and Stratum 2 payload; third, computing time drift and transit delay; fourth, adjusting the local clock and incrementing stratum to 3; and fifth, marking the verified peer as synchronized (∗*) in system output.

Adım Adım Çözüm

1
Initiate NTP request
The router sends a client mode NTP packet on UDP port 123.
Synchronization begins when the client actively polls the configured NTP server.
2
Receive server payload
The server sends back an NTP packet indicating Stratum 2 and authoritative timestamp info.
The server provides the reference time data needed for calculation.
3
Compute clock offset and network delay
The router uses the four timestamps (origin, receive, transmit, destination) to determine offset.
Transit delay must be accounted for to accurately adjust the local clock.
4
Adjust system time and increment stratum
System clock is synchronized and stratum becomes 3 (2+12 + 1).
An NTP client's stratum is defined as the server's stratum plus one hop distance.
5
Flag active system peer
The peer displays an asterisk (∗*) in `show ntp associations`.
The asterisk denotes the configured NTP source currently selected for system clock synchronization.

Anahtar Kavram

NTP Client-Server Synchronization Sequence and Stratum Hierarchy Propagation
Soru 576Soru →

Four OSPFv2 routers are connected to a shared multi-access Ethernet segment. Place the steps of the OSPF Designated Router (DR) election logic in the correct order of evaluation, from the initial eligibility filter to the final operational behavior.

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The correct operational sequence is: Exclude routers with an OSPF priority of 0, select the candidate with the highest interface priority, break ties using the highest OSPF Router ID, and finally enforce non-preemption so an established DR remains active.
On multi-access broadcast networks, OSPF DR/BDR election begins by filtering out any router configured with priority 0. For remaining eligible routers, the router with the highest OSPF interface priority is preferred. If priorities are equal, the router with the highest Router ID breaks the tie. Once a DR is elected, the process is non-preemptive, meaning new routers joining the segment will not replace an active DR even if they have superior metrics.

Adım Adım Çözüm

1
Filter out non-candidate routers.
Routers with `ip ospf priority 0` are excluded from election participation.
Setting priority to 0 explicitly forces a router to remain a DROTHER.
2
Evaluate interface priority values.
The candidate with the highest interface priority (range 1-255) is designated as winner.
Interface priority is the primary metric in OSPF DR/BDR elections.
3
Evaluate Router IDs if priorities match.
The router with the highest Router ID is selected.
Router ID acts as the definitive tie-breaker when OSPF priorities are tied.
4
Apply non-preemptive election rules.
The elected DR retains its role until the process or link resets.
OSPF prevents network instability and adjacencies reset by disallowing preemption.

Anahtar Kavram

OSPFv2 DR/BDR Election Logic and Precedence Rules
Soru 577Soru →

A network administrator connects to a Cisco IOS router via SSH to troubleshoot a line protocol issue. After establishing the session, the administrator executes the command `terminal monitor`. Assuming the router is running default syslog configurations, which range of syslog severity levels will be displayed in this SSH terminal session?

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Cevap: All syslog messages with severity levels 0 (Emergency) through 7 (Debugging)

Cevap

All syslog messages with severity levels 0 (Emergency) through 7 (Debugging) will be displayed in the session.
In Cisco IOS, the default logging severity level for terminal monitor logging is level 7 (Debugging). Syslog thresholds operate inclusively for all severity levels equal to or lower than the configured numerical value. Because severity 0 (Emergency) is the most critical and severity 7 (Debugging) is the least critical, setting or inheriting the default level 7 monitor threshold allows messages of all severities (0 through 7) to be output to the active VTY session once `terminal monitor` is enabled.

Adım Adım Çözüm

1
Identify the function of the `terminal monitor` command.
The `terminal monitor` command enables the redirection of syslog messages to the active VTY (SSH/Telnet) session for the current user.
VTY sessions do not display syslog messages by default, unlike the physical console port.
2
Determine the default logging severity threshold for monitor logging in Cisco IOS.
The default severity level threshold for monitor logging is level 7 (Debugging).
Cisco IOS sets default logging thresholds for console, monitor, and buffered logging to debugging (level 7).
3
Evaluate how syslog threshold logic operates.
A logging threshold includes the specified severity level and all levels with lower numerical values (higher criticality).
Syslog severity ranges from 0 (Emergency) to 7 (Debugging). Therefore, a threshold of 7 includes all messages from 0 up to 7.

Anahtar Kavram

Cisco IOS Monitor Logging Default Severity Thresholds
Tahmini Süre:1m 30s
Soru 578Soru →

A network administrator wants to encrypt all cleartext passwords stored in a Cisco IOS router's running configuration file, including console line passwords and legacy user passwords. Which global configuration command accomplishes this task?

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Cevap: service password-encryption

Cevap

The command 'service password-encryption' globally obfuscates all current and future cleartext passwords in the configuration file using Type 7 encryption.
Executing 'service password-encryption' in global configuration mode instructs Cisco IOS to apply Cisco Type 7 encryption to all stored plain-text passwords in the running configuration, such as those set via 'line console 0' or legacy 'username' commands.

Adım Adım Çözüm

1
Identify the goal
The requirement is to convert existing and future plain-text passwords across line configurations and local accounts into encrypted strings within the running configuration.
By default, commands like 'password' under line configuration or legacy 'username password' store passwords in plain text.
2
Evaluate Cisco IOS commands for configuration-wide password obfuscation
Entering 'service password-encryption' in global configuration mode immediately encrypts all unencrypted passwords using Cisco Type 7 encryption.
This command specifically targets configuration file display security rather than individual authentication modes.

Anahtar Kavram

Cisco IOS Global Password Encryption
Soru 579Soru →

A network engineer is configuring logging thresholds on a Cisco IOS router and needs to categorize Syslog severity levels according to their standard numerical hierarchy. Arrange the following Syslog severity names in order from the MOST severe (lowest numerical level) to the LEAST severe (highest numerical level).

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Cevap

The correct order from most severe (lowest numerical value) to least severe (highest numerical value) is: Critical (level 2), Error (level 3), Warning (level 4), and Informational (level 6).
Syslog levels range from 0 (Emergency) down to 7 (Debugging). Ordering the specified levels from most severe to least severe requires listing them in ascending order of their numerical values: Critical (2), Error (3), Warning (4), and Informational (6).

Adım Adım Çözüm

1
Identify the numerical Syslog severity level assigned to each named severity.
Critical = Level 2, Error = Level 3, Warning = Level 4, Informational = Level 6.
Cisco IOS Syslog protocol assigns integer values from 0 (most urgent) to 7 (least urgent).
2
Sort the severity names by their numerical levels in ascending order.
Level 2 (Critical) < Level 3 (Error) < Level 4 (Warning) < Level 6 (Informational).
Lower numerical values indicate higher severity and greater urgency.
3
Construct the final sequence based on the sorted values.
Critical -> Error -> Warning -> Informational.
This sequence properly orders the Syslog messages from highest urgency to lowest urgency.

Anahtar Kavram

Cisco IOS Syslog Severity Levels and Hierarchy
Soru 580Soru →

A network administrator configures the command `ip ospf network point-to-point` on interface GigabitEthernet0/1 of router R1, which connects directly to router R2 over an Ethernet segment in OSPFv2 Area 0. Which operational change occurs on this interface as a result of this configuration?

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Cevap: OSPF suppresses Designated Router (DR) and Backup Designated Router (BDR) elections on the interface while maintaining the default 10-second Hello timer.

Cevap

OSPF suppresses Designated Router (DR) and Backup Designated Router (BDR) elections on the interface while maintaining the default 10-second Hello timer.
On point-to-point OSPF networks, DR and BDR elections are completely suppressed because only two routers reside on the link. The default Hello and Dead timers for point-to-point network types on Ethernet media remain 10 seconds and 40 seconds, respectively.

Adım Adım Çözüm

1
Analyze default OSPF behavior on Ethernet interfaces.
Ethernet interfaces default to the OSPF Broadcast network type, which requires DR/BDR election and uses Hello/Dead timers of 10s/40s.
Broadcast multiaccess networks elect a DR and BDR to reduce adjacency overhead on shared segments.
2
Evaluate the effect of the `ip ospf network point-to-point` command.
Changing the network type to point-to-point informs OSPF that only two routers exist on the link, rendering DR/BDR elections unnecessary.
Point-to-point OSPF network types do not elect a DR or BDR and establish FULL neighbor adjacencies directly between the two endpoints.
3
Verify timer changes associated with the Point-to-Point network type.
Point-to-Point interfaces retain the standard 10-second Hello and 40-second Dead timer defaults.
Only Non-Broadcast (NBMA) and Point-to-Multipoint network types change default timers to 30s/120s.

Anahtar Kavram

OSPFv2 Network Types and DR/BDR Election Behavior
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