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Tüm alıştırma soruları

1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 1601Soru →

An administrator needs to configure Port Address Translation (PAT) on a Cisco IOS router to allow multiple internal hosts matched by Access Control List 15 to share the single IPv4 address assigned to interface GigabitEthernet0/1 for internet access. Which command correctly enables this configuration?

Cevabı ve açıklamayı göster

Cevap: ip nat inside source list 15 interface GigabitEthernet0/1 overload

Cevap

The command 'ip nat inside source list 15 interface GigabitEthernet0/1 overload' correctly configures Port Address Translation (PAT).
The command stating 'ip nat inside source list 15 interface GigabitEthernet0/1 overload' is correct because it properly binds inside source traffic allowed by ACL 15 to the interface's IP address and appends the 'overload' keyword, enabling PAT (Port Address Translation) via TCP/UDP port mapping.

Adım Adım Çözüm

1
Identify the requirement for translating multiple private IP addresses to a single interface IP address.
Port Address Translation (PAT) using the overload keyword on an interface is required.
The overload keyword allows multiple internal IP addresses to map to a single public IP address using distinct layer 4 source port numbers.
2
Construct the Cisco IOS configuration syntax for interface-based PAT.
The correct command syntax is 'ip nat inside source list <acl> interface <type/number> overload'.
This binds the inside source traffic matched by the specified ACL to the outbound interface IP address with port overloading.

Anahtar Kavram

Port Address Translation (PAT) Configuration using Interface Overload
Soru 1602Soru →

A network administrator needs to carve out a new subnetwork from the 172.16.64.0/22172.16.64.0/22 enterprise address block for a remote branch office. The branch requires static IPv4 addresses for 2626 workstation PCs, 22 IP phones, and 22 network printers. Which IPv4 network address and prefix length combination provides the most efficient assignment to accommodate all required host addresses without wasting address space?

Cevabı ve açıklamayı göster

Cevap: 172.16.64.0/27172.16.64.0/27

Cevap

The most efficient subnet assignment is 172.16.64.0/27172.16.64.0/27 because it provides exactly 30 usable IPv4 addresses within the valid RFC 1918 private block.
The required endpoint count is 30 hosts (26+2+2=3026 + 2 + 2 = 30). To accommodate 30 usable hosts, 5 host bits are needed (25−2=302^5 - 2 = 30). Subtracting 5 host bits from 32 IPv4 total bits leaves a /27 prefix. Subnetwork 172.16.64.0/27172.16.64.0/27 resides within the allocated 172.16.64.0/22172.16.64.0/22 block and RFC 1918 private space, fulfilling all requirements with zero wasted IP addresses.

Adım Adım Çözüm

1
Calculate the total host IP address requirement
Total endpoints = 26 PCs+2 phones+2 printers=30 usable IP addresses26 \text{ PCs} + 2 \text{ phones} + 2 \text{ printers} = 30 \text{ usable IP addresses}.
All active physical and virtual endpoints require individual host IPv4 addresses on the subnetwork.
2
Determine the host bit requirement (hh)
Using 2h−2≥302^h - 2 \ge 30, solving for hh yields h=5h = 5 host bits (25−2=302^5 - 2 = 30).
Two IP addresses per subnet are unassignable to hosts: the network address (all host bits set to 0) and the subnet broadcast address (all host bits set to 1).
3
Calculate the subnet prefix length
Prefix length = 32−5=/2732 - 5 = /27.
Subtracting the 5 host bits from the 32 total bits in an IPv4 address defines the 27 network prefix bits.
4
Verify address space validity and boundaries
Subnetwork 172.16.64.0/27172.16.64.0/27 falls within the 172.16.64.0/22172.16.64.0/22 parent block and belongs to the RFC 1918 private Class B range (172.16.0.0−172.31.255.255172.16.0.0 - 172.31.255.255).
Internal enterprise subnets must utilize allocated private address space.

Anahtar Kavram

IPv4 Subnet Sizing and Usable Host Calculation
Soru 1603Soru →

A network administrator is configuring a backup link on a Cisco router for destination network 10.50.0.0/2410.50.0.0/24. The primary path to this network is currently learned via OSPF, which has a default Administrative Distance (AD) of 110110. Which two statements correctly describe the requirements and operational behavior of the floating static route used for this backup path? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The administrative distance configured at the end of the static route command must be greater than 110110.; The floating static route will only be installed into the active routing table if the primary OSPF route is removed.

Cevap

The floating static route must be configured with an administrative distance higher than the primary routing protocol's AD (greater than 110 for OSPF), and it will only populate the routing table when the primary OSPF route is removed.
A floating static route serves as a backup path by assigning an Administrative Distance (AD) higher than that of the primary routing protocol (OSPF AD = 110). Because Cisco IOS prefers routes with lower AD values, the floating static route is held in inactive standby and is only placed into the active routing table when the primary OSPF route disappears.

Adım Adım Çözüm

1
Identify the primary routing protocol and its default Administrative Distance (AD).
The primary route is OSPF, which carries a default AD of 110110.
Administrative Distance determines the trustworthiness of routing sources in Cisco IOS.
2
Determine the required AD for the floating static route to function as a backup.
The static route AD must be set to a value higher than 110110 (such as 120120).
Lower AD values are preferred. Setting a higher AD ensures the static route is ignored as long as the OSPF route is present in the routing table.
3
Analyze how Cisco IOS installs the floating static route into the routing table.
The floating static route remains inactive in configuration until the OSPF route fails or is withdrawn, at which point the router installs the backup static route.
A router only installs the route with the lowest AD for a given prefix into the active routing table.

Anahtar Kavram

Floating Static Route Administrative Distance and Failover Mechanics
Tahmini Süre:1m 30s
Soru 1604Soru →

An network engineer is analyzing how OSPFv2 resolves Designated Router (DR) selection on a multiaccess Ethernet segment when multiple candidate routers initialize simultaneously. Arrange the tie-breaking criteria in order of evaluation precedence, starting with the primary criterion evaluated first (highest precedence) at the top down to the final fallback tie-breaker at the bottom.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct evaluation sequence for OSPF DR selection precedence is: 1. Highest OSPF interface priority value (1–255), 2. Explicitly configured OSPF router ID (`router-id` command), 3. Highest IP address among active loopback interfaces, and 4. Highest IP address among active physical interfaces.
During an OSPF DR/BDR election on a broadcast multiaccess segment, routers first compare interface priority values (1 to 255). If priorities are tied, the election uses the OSPF Router ID as the tie-breaker. The Router ID selection hierarchy itself evaluates an explicitly configured router ID first, followed by the highest active loopback IP address, and finally the highest active physical interface IP address.

Adım Adım Çözüm

1
Identify the primary parameter evaluated during OSPF DR/BDR elections on multiaccess networks.
OSPF interface priority is evaluated first. Priority values range from 0 to 255, where priority 0 disables election participation and higher values win.
Interface priority explicitly allows network administrators to control DR/BDR roles regardless of IP addressing.
2
Determine the highest precedence method for tie-breaking using the OSPF Router ID when interface priorities match.
An explicitly configured `router-id` under the OSPF router process is evaluated first.
Manual CLI configuration overrides all dynamic IP address collection logic.
3
Identify the dynamic fallback method for Router ID derivation when no manual Router ID is set.
The highest IPv4 address on any active (up/up) loopback interface is chosen.
Loopback interfaces are preferred over physical interfaces due to their logical stability.
4
Identify the final fallback method for Router ID derivation.
The highest IPv4 address on any active (up/up) physical interface is chosen.
Physical interface IP addresses serve as the last-resort tie-breaker when no explicit router ID or loopbacks are present.

Anahtar Kavram

OSPF DR/BDR election logic prioritizes interface priority first, using Router ID (derived via explicit CLI > highest loopback IP > highest physical IP) as a sequential tie-breaker.
Soru 1605Soru →

A network engineer is troubleshooting an OSPFv2 neighbor relationship between router R1 and router R2 connected across a shared Ethernet segment. Command output from `show ip ospf neighbor` on R1 displays R2 in the `INIT/ -` state. Which condition is the primary cause of the neighbor relationship being stuck in the INIT state?

Cevabı ve açıklamayı göster

Cevap: An access control list is blocking OSPF Hello packets sent from R1 to R2, resulting in unidirectional communication

Cevap

An access control list is blocking OSPF Hello packets sent from R1 to R2, resulting in unidirectional communication.
The INIT state indicates that R1 has successfully received OSPF Hello packets from R2, but R1 has not seen its own Router ID listed in R2's Hello packet. This scenario occurs when traffic flow is unidirectional—such as when an inbound or outbound Access Control List (ACL) blocks OSPF Hello packets transmitted from R1 to R2 while allowing Hellos from R2 to reach R1.

Adım Adım Çözüm

1
Analyze OSPF neighbor state machine progression for the INIT state
The INIT state means a router has received an OSPF Hello packet from a neighbor, but its own Router ID is NOT present in the list of seen neighbors contained within that Hello packet.
Transitioning beyond INIT to 2-Way requires bi-directional communication, where both routers acknowledge receiving each other's Hello packets.
2
Evaluate the cause of unidirectional Hello reception
If R1 receives R2's Hellos, R1 transitions R2 to the INIT state. If R2 never receives R1's Hellos (e.g., due to an ACL filtering packets from R1 to R2), R2 will not include R1's Router ID in its outgoing Hellos.
Without R1's Router ID in R2's Hello packet, R1 cannot transition the neighbor relationship to 2-Way, leaving it permanently stuck in INIT.
3
Distinguish INIT state causes from DOWN and EXSTART state causes
Mismatches in Area ID, Hello/Dead timers, subnet mask, or authentication cause Hello packets to be dropped on arrival, keeping the neighbor in DOWN state. MTU mismatches cause neighbors to get stuck in EXSTART/EXCHANGE state.
Identifying which parameters are checked during Hello validation pinpoints why other mismatches fail earlier (DOWN) or later (EXSTART) in the adjacency process.

Anahtar Kavram

OSPF Neighbor Adjacency States and Unidirectional Communication Troubleshooting
Soru 1606Soru →

An administrator modifies the OSPFv2 network type on a GigabitEthernet interface shared by two routers from the default BROADCAST to POINT_TO_POINT using the command `ip ospf network point-to-point`. Which two statements correctly describe the operational changes resulting from this configuration? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Designated Router (DR) and Backup Designated Router (BDR) elections are bypassed on the interface.; OSPF packets continue to be sent to the AllSPFRouters multicast address (224.0.0.5), but the AllDRouters address (224.0.0.6) is no longer used.

Cevap

On an OSPFv2 Point-to-Point network link, DR/BDR elections are entirely bypassed, and routers communicate using the AllSPFRouters multicast address (224.0.0.5) while discontinuing the use of 224.0.0.6.
Configuring `ip ospf network point-to-point` changes OSPF operating behavior such that DR and BDR elections are omitted because the link connects only two endpoints. In addition, all OSPF traffic (Hello, DBD, LSU, LSAck) on a point-to-point link uses the 224.0.0.5 multicast destination address, omitting 224.0.0.6.

Adım Adım Çözüm

1
Analyze DR/BDR requirements for Point-to-Point network types.
Recognize that Point-to-Point links connect exactly two routers, making DR/BDR election unnecessary.
DR and BDR roles exist solely to reduce adjacency flood overhead on multiaccess networks.
2
Evaluate OSPF multicast address usage on Point-to-Point links.
Identify that 224.0.0.5 (AllSPFRouters) is used for all OSPF packet exchanges on Point-to-Point links, while 224.0.0.6 (AllDRouters) is unused.
Since there is no DR present on the segment, packets destined to DRs (224.0.0.6) are unnecessary.
3
Compare default timers and neighbor discovery behavior between Broadcast and Point-to-Point modes.
Confirm that both network types default to 10-second Hello and 40-second Dead timers and both dynamically discover neighbors via multicast.
Only NBMA and Point-to-Multipoint modes use 30/120 second default timers or require static neighbor statements.

Anahtar Kavram

OSPFv2 Point-to-Point vs Broadcast Network Type Characteristics
Soru 1607Soru →

A network engineer is connecting multiple physical distribution system ports of a Cisco AireOS Wireless LAN Controller (WLC) to an upstream Cisco Catalyst switch using Link Aggregation (LAG). Which two configuration requirements must be implemented on the switch interfaces to establish successful aggregation and traffic transport? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Configure the EtherChannel bundle mode on the switch interfaces to static 'on' state.; Configure the switch interface or port-channel as an 802.1Q trunk port to carry traffic across multiple VLANs.

Cevap

The correct requirements are configuring the switch interfaces to static EtherChannel mode ('on') and setting the link to operate as an 802.1Q trunk.
Cisco AireOS WLCs utilize static Link Aggregation (LAG) and do not support dynamic EtherChannel negotiation protocols like LACP or PAgP. Consequently, switch ports connected to an AireOS controller must be set to static mode ('channel-group mode on'). Furthermore, since LAG bundles all physical controller ports into a single logical connection handling multiple SSIDs and management traffic, the upstream switch interface must be configured as an 802.1Q trunk port.

Adım Adım Çözüm

1
Determine controller LAG protocol support.
AireOS WLCs support static Link Aggregation (LAG) without using dynamic negotiation protocols such as LACP or PAgP.
Because the controller does not exchange LACP or PAgP packets, the switch ports must force EtherChannel creation using 'channel-group mode on'.
2
Determine switchport trunking configuration.
Configure the switch port-channel as an 802.1Q trunk carrying management and dynamic client VLANs.
Enabling LAG on a WLC aggregates all physical distribution ports into a single trunk link capable of carrying untagged management traffic and tagged dynamic client VLAN traffic.

Anahtar Kavram

Cisco AireOS WLC Link Aggregation (LAG) and Switchport Trunking Requirements
Soru 1608Soru →

A network engineer is configuring Port Address Translation (PAT) using an IP address pool on a Cisco IOS router. An access list named ACL_LAN (ACL 10) matches internal traffic, and an IP address pool named GIG_POOL has been defined for global addresses. What exact global configuration command completes this PAT configuration by linking access list 10 to GIG_POOL with port overload capability?

Cevabı ve açıklamayı göster

Cevap: ip nat inside source list 10 pool GIG_POOL overload; ip nat inside source list 10 pool GIG_POOL overload

Cevap

ip nat inside source list 10 pool GIG_POOL overload
The command 'ip nat inside source list 10 pool GIG_POOL overload' explicitly binds internal traffic defined by ACL 10 to the public address pool GIG_POOL while enabling port overloading (PAT).

Adım Adım Çözüm

1
Identify the standard access list matching inside traffic.
Access list 10 matches internal subnets.
NAT source list parameter requires referencing the defined access list number or name.
2
Identify the target public IP address pool name.
The NAT pool name is specified as GIG_POOL.
The pool keyword requires the exact name of the previously configured IP address pool.
3
Append the port address translation overload keyword.
Adding overload allows multiple inside local addresses to share public IP addresses in the pool using layer 4 port numbers.
Omitting overload configures dynamic one-to-one NAT without port multiplexing, causing address exhaustion when pool IP addresses are fully allocated.

Anahtar Kavram

Inside source Port Address Translation (PAT) using an IP address pool requires the overload keyword appended to the 'ip nat inside source list <acl> pool <pool-name>' command.
Soru 1609Soru →

Two routers are connected across an Ethernet link and configured for OSPFv2 routing. Which TWO parameters exchanged in the OSPF Hello packet must match identically between the two routers for an OSPFv2 neighbor adjacency to form successfully?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Area ID configured on the connected interfaces; Hello and Dead timer intervals

Cevap

The OSPF Area ID and the Hello and Dead timer intervals must match identically between neighboring routers.
For two OSPFv2 routers to establish a neighbor adjacency, specific parameters inside their Hello packets must be identical. These include the Area ID configured on the interface, the Hello and Dead timer intervals, the IP subnet mask (on broadcast/multiaccess links), and any stub/area option flags.

Adım Adım Çözüm

1
Analyze OSPF Hello packet fields required for neighbor establishment
Identified mandatory match criteria: Area ID, Hello/Dead timers, Subnet Mask (on multiaccess networks), Stub area flag, and Authentication.
OSPF neighbor discovery requires agreement on basic link parameters before transitioning beyond the Init state.
2
Evaluate local vs global OSPF configuration settings
Process ID is purely local to the router process and is omitted from Hello packet negotiation.
Different routers in the same network can use different OSPF process IDs (e.g., Process 1 on R1 and Process 10 on R2).
3
Evaluate Router ID uniqueness requirements
Router IDs must be unique across the OSPF domain.
Duplicate Router IDs cause neighbor adjacencies to flap or fail to form.

Anahtar Kavram

OSPFv2 Hello Packet Mandatory Match Parameters
Soru 1610Soru →

A network administrator is writing an automation script to interact with a Cisco DNA Center REST API. The script needs to perform a full update of an existing network device configuration object by replacing its attributes on the server. Which HTTP verb should the script use?

Cevabı ve açıklamayı göster

Cevap: PUT

Cevap

The HTTP PUT verb is used to perform a full update or replacement of an existing resource.
In REST-based APIs, the HTTP PUT method maps directly to the Update operation in the CRUD model when performing a complete replacement of an existing resource.

Adım Adım Çözüm

1
Identify the target CRUD operation requested
The requirement specifies modifying/replacing an existing configuration object on the server.
Mapping the operational goal to CRUD determines the appropriate HTTP verb.
2
Map the Update operation to the corresponding HTTP verb
In RESTful architecture, HTTP PUT performs a full update/replacement of an existing resource.
PUT replaces the resource representation completely at the specified URI.

Anahtar Kavram

REST API HTTP Verbs and CRUD Mapping
Tahmini Süre:45s
Soru 1611Soru →

A network administrator is configuring Port Address Translation (PAT) on a Cisco IOS router to allow internal users access to the Internet using a single public IP address assigned to the GigabitEthernet0/1 interface. The administrator has already configured the Access Control List (ACL) and the inside/outside interfaces. What exact Cisco IOS keyword must be appended to the end of the 'ip nat inside source list 1 interface GigabitEthernet0/1' command to enable port-level address translation?

Cevabı ve açıklamayı göster

Cevap: overload; the overload keyword; overload keyword

Cevap

overload
The 'overload' keyword instructs the Cisco IOS router to perform Port Address Translation (PAT), enabling multiple private IPv4 addresses to share a single public IP address by tracking source port numbers.

Adım Adım Çözüm

1
Identify the requirement for Port Address Translation (PAT) using an interface IP address.
PAT enables multiple private IP addresses to share a single public IP address by mapping distinct layer 4 port numbers.
Without the overload capability, static NAT or standard dynamic NAT requires a 1-to-1 IP mapping.
2
Determine the necessary Cisco IOS command syntax.
The command syntax is 'ip nat inside source list <acl> interface <interface> overload'.
The 'overload' keyword specifically enables PAT, allowing port tracking for dynamic address translation.

Anahtar Kavram

Port Address Translation (PAT) Interface Overload Syntax
Soru 1612Soru →

An administrator is reviewing DNS lookup behaviors and transport protocol characteristics for enterprise host name resolution. Which two statements correctly describe DNS operations and protocol roles during name resolution? (Choose two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Standard client DNS query requests and small responses typically use UDP port 53 to reduce latency and header overhead.; DNS switches to TCP port 53 when a response payload exceeds the standard buffer limit or during zone transfers between DNS servers.

Cevap

Standard client DNS queries primarily use UDP port 53 to minimize transport overhead, but DNS fallback to TCP port 53 occurs when response sizes exceed buffer limits or during server-to-server zone transfers.
DNS queries use UDP port 53 by default because connectionless transport reduces overhead and latency for simple lookups. When response data exceeds standard message length thresholds or during DNS zone transfers between servers, DNS relies on TCP port 53 for reliable connection-oriented delivery.

Adım Adım Çözüm

1
Identify standard DNS transport behavior for general host queries.
DNS uses UDP port 53 for simple queries and responses to maintain low connection establishment overhead and quick lookups.
UDP is connectionless and optimized for lightweight request-response exchanges.
2
Identify conditions where DNS uses TCP instead of UDP.
TCP port 53 is used when response messages are truncated (exceeding standard UDP buffer size) or during bulk data synchronization such as zone transfers.
TCP provides reliable, stream-oriented delivery for large payloads or state transfers.

Anahtar Kavram

DNS Transport Protocols and Server Resolution Roles
Soru 1613Soru →

A network administrator is evaluating the operation of DNS protocol mechanisms and transport layer behavior within an enterprise network infrastructure. Which two statements accurately describe how DNS lookup processes and transport protocols function during name resolution? (Choose two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Standard DNS queries for IP address resolution (A or AAAA records) typically utilize UDP port 53 to reduce latency and connection overhead.; When a DNS response payload exceeds 512 bytes without EDNS0 support, the server sets the TrunCation (TC) bit, prompting the client to re-query using TCP port 53.

Cevap

The two correct statements are that standard DNS queries for IP address resolution typically utilize UDP port 53 to reduce latency, and when a DNS response payload exceeds 512 bytes without EDNS0 support, the server sets the TrunCation (TC) bit to prompt the client to re-query using TCP port 53.
Standard DNS lookups operate over UDP port 53 because single-packet requests and responses do not warrant the overhead of a TCP connection. However, if a DNS response message is truncated due to exceeding 512 bytes (without extension mechanisms like EDNS0), the DNS server sets the TC (TrunCation) bit in the header. Upon receiving a truncated response, the client initiates a TCP connection on port 53 to reliably retrieve the complete set of resource records.

Adım Adım Çözüm

1
Identify the primary transport protocol used for standard DNS queries.
DNS uses UDP port 53 for normal client-to-server and server-to-server queries to maintain low latency and minimize connection overhead.
Establishing a TCP connection for small request/response pairs adds unnecessary delay.
2
Determine the conditions under which DNS transitions from UDP to TCP transport.
DNS falls back to TCP port 53 when the response exceeds 512 bytes (indicated by the TC bit in the DNS header) or during DNS zone transfers (AXFR/IXFR).
TCP guarantees reliable delivery and reassembly for large payloads that cannot fit into standard UDP DNS packets.

Anahtar Kavram

DNS Transport Protocols and TrunCation (TC) Mechanism
Soru 1614Soru →

When a Cisco router receives an IPv4 unicast packet and must select the single best route for forwarding from multiple potential routing table candidates, in what sequence does the router apply its decision logic? Place the steps in the correct order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct order of router decision logic is: 1) Inspect the packet header to extract the destination IPv4 address, 2) Filter candidate routes using Longest Prefix Match (most specific subnet mask length), 3) Compare Administrative Distance (AD) to select the most believable routing source among identical prefix length matches, 4) Compare routing protocol metrics to choose the lowest cost path among identical prefix matches from the same protocol, and 5) Determine the next-hop IPv4 address and associated outbound interface from the selected best route entry.
Router forwarding decision logic follows a strict order of operations: First, the destination IPv4 address is read from the packet header. Second, the router searches its routing table for candidate routes and selects the longest prefix match (most specific mask). Third, if multiple routes have identical subnet mask lengths from different routing sources, Administrative Distance (AD) is evaluated to pick the lowest AD source. Fourth, if identical prefix routes come from the same routing source, the metric is evaluated to select the lowest cost path. Finally, the next-hop IP and egress interface are resolved for forwarding.

Adım Adım Çözüm

1
Identify initial packet processing.
Destination IPv4 address is extracted from the IPv4 header.
The router needs the target IP address before searching the routing table.
2
Apply Longest Prefix Match (LPM).
Candidate routes are evaluated strictly by prefix length (number of matching subnet mask bits).
LPM is the primary criterion in IPv4 forwarding. AD and metric are ignored until LPM narrows candidates to identical prefix lengths.
3
Evaluate Administrative Distance (AD).
If a tie exists in prefix length between different routing sources, the route with the lowest AD is selected.
AD measures route believability/trustworthiness across different routing sources.
4
Evaluate protocol metric.
If candidate routes have identical prefix lengths and originate from the same routing protocol, the path with the lowest metric is chosen.
Metric measures the internal path cost for a specific routing protocol.
5
Extract forwarding parameters.
The router obtains the egress interface and next-hop IP address for packet encapsulation.
This information is needed to build the new Layer 2 frame and transmit the packet.

Anahtar Kavram

Router Forwarding Decision Hierarchy (LPM -> AD -> Metric -> Next-Hop Extraction)
Tahmini Süre:1m 30s
Soru 1615Soru →

Router Edge-1 is connected to a primary service provider using external BGP (eBGP, Administrative Distance 20) and a secondary service provider using an IPv4 static route to reach destination network 192.168.100.0/24192.168.100.0/24. The network engineer intends for the static route to serve strictly as a floating backup path that only activates if the primary eBGP route fails. During a routing table audit, the engineer discovers that the static route is active in the routing table even while the primary eBGP link is fully operational.

The current static route configuration on Edge-1 is:
`ip route 192.168.100.0 255.255.255.0 10.0.12.2 15`

Which configuration change on router Edge-1 will ensure that the static route functions correctly as a backup path?

Cevabı ve açıklamayı göster

Cevap: Reconfigure the static route as `ip route 192.168.100.0 255.255.255.0 10.0.12.2 25` so its administrative distance exceeds that of eBGP.

Cevap

Reconfigure the static route as `ip route 192.168.100.0 255.255.255.0 10.0.12.2 25` so its administrative distance exceeds that of eBGP.
A floating static route serves as a backup path and must have an Administrative Distance (AD) configured higher than that of the primary route source. Since eBGP routes have a default AD of 20, setting the static route's AD to 25 ensures it will only be installed into the routing table if the primary eBGP route fails.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary routing protocol.
eBGP has a default Administrative Distance of 20.
Administrative Distance measures route trustworthiness; lower AD values are preferred by the routing table.
2
Analyze why the current static route is active in the routing table.
The current static route has an explicit AD of 15, which is lower than eBGP (20).
Because 15 < 20, the router selects the static route as the primary path instead of treating it as a backup.
3
Determine the AD requirement for a floating static route.
The static route's AD must be set to a value strictly greater than 20 (e.g., 25).
Setting the AD higher than the primary routing protocol ensures the static route remains inactive in the RIB until the primary eBGP route is withdrawn.

Anahtar Kavram

Floating Static Route Administrative Distance Calibration
Tahmini Süre:2m 0s
Soru 1616Soru →

An administrator is configuring first-hop redundancy on router R1 for VLAN 50 using HSRPv2. Interface GigabitEthernet0/0/0 on R1 is assigned the IPv4 address 192.168.50.1/24192.168.50.1/24. The administrator enters interface configuration mode and issues the command `standby 50 ip 192.168.50.1` to establish the virtual IP address. Which outcome will result from this configuration attempt?

Cevabı ve açıklamayı göster

Cevap: The command line interface rejects the command because HSRP forbids assigning a router's physical interface IPv4 address as the virtual IP address.

Cevap

The command line interface rejects the command because HSRP forbids assigning a router's physical interface IPv4 address as the virtual IP address.
In Cisco HSRP implementation, the virtual IPv4 address must be an unused IP address on the subnet segment. It cannot match the physical IP address assigned to any interface on any router participating in the HSRP group. Attempting to assign an existing physical IP address causes Cisco IOS to reject the `standby ip` command with a syntax validation error.

Adım Adım Çözüm

1
Analyze the HSRP virtual IP assignment rule in Cisco IOS.
HSRP (both v1 and v2) mandates that the virtual IPv4 address must be an unassigned IP within the subnet segment, strictly distinct from any physical IP configured on participating routers.
Preventing IP overlaps ensures ARP resolution and virtual MAC binding operate without address conflicts.
2
Compare HSRP rules with VRRP rules regarding IP address ownership.
Unlike VRRP—where configuring the virtual IP to match a master router's physical IP address is allowed and automatically sets the VRRP priority to 255 (IP address owner)—HSRP does not support IP address ownership.
HSRP syntax validation rejects physical IP matches at CLI input time.
3
Determine the CLI outcome when `standby 50 ip 192.168.50.1` is entered on R1.
Cisco IOS generates an error message (such as `% Bad IP address` or `% Address on interface cannot be used as HSRP virtual IP`) and rejects the statement.
The input violates core HSRP validation rules.

Anahtar Kavram

HSRP Virtual IP Addressing vs VRRP IP Address Ownership
Tahmini Süre:1m 30s
Soru 1617Soru →

A network administrator needs to create VLAN 35 named SALES on a Cisco Catalyst switch and assign interface FastEthernet0/5 as a static access port in this VLAN, starting from Privileged EXEC mode (`Switch#`). Place the following Cisco IOS CLI commands in the correct sequential order from first to last.

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Cevap

The correct command sequence begins with entering global configuration mode using `configure terminal`, creating VLAN 35 using `vlan 35`, setting the VLAN name with `name SALES`, entering the interface context via `interface FastEthernet0/5`, configuring the interface operating mode using `switchport mode access`, and finally assigning the interface to the VLAN using `switchport access vlan 35`.
In Cisco IOS, configuration follows a strict hierarchy. From Privileged EXEC mode (`Switch#`), global configuration mode must first be accessed via `configure terminal`. Once in global configuration mode, `vlan 35` creates the VLAN and shifts context to VLAN sub-mode (`config-vlan`), where `name SALES` sets the VLAN name. The administrator then navigates directly to interface configuration mode using `interface FastEthernet0/5`. Within interface configuration mode (`config-if`), the port mode is explicitly configured using `switchport mode access`, followed by assigning the port to VLAN 35 with `switchport access vlan 35`.

Adım Adım Çözüm

1
Enter Global Configuration Mode
Prompt changes from `Switch#` to `Switch(config)#`.
Global configuration commands like VLAN creation and interface navigation can only be initiated from global configuration mode.
2
Create VLAN 35
Prompt changes from `Switch(config)#` to `Switch(config-vlan)#`.
Issuing `vlan 35` creates the Layer 2 broadcast domain in the VLAN database and opens VLAN configuration mode.
3
Assign VLAN Name
VLAN 35 is assigned the name SALES in the switch database.
The `name` command must be run while in VLAN configuration mode.
4
Navigate to Interface FastEthernet0/5 Context
Prompt changes to `Switch(config-if)#`.
Interface parameters can only be altered when inside the specific interface configuration sub-mode.
5
Set Port Operational Mode to Access
Dynamic Trunking Protocol (DTP) negotiation is disabled or restricted, locking the port to non-trunking access mode.
Executing `switchport mode access` explicitly sets the interface into access mode before or during VLAN membership assignment.
6
Associate Interface with VLAN 35
Traffic untagged on FastEthernet0/5 is assigned to VLAN 35.
The command `switchport access vlan 35` binds the interface to the specified access VLAN.

Anahtar Kavram

Cisco IOS CLI command hierarchy for VLAN creation and static access port configuration
Soru 1618Soru →

A network administrator needs to configure a Cisco IOS router to synchronize its internal clock with an external centralized time source at IP address 192.168.10.50. Which Cisco IOS global configuration command must be used to accomplish this task?

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Cevap: ntp server 192.168.10.50

Cevap

The command 'ntp server 192.168.10.50' configures the router to act as an NTP client synchronizing from the specified NTP server.
The correct command is 'ntp server 192.168.10.50'. In Cisco IOS, entering 'ntp server' followed by an IP address configures the router to request time updates from that remote server.

Adım Adım Çözüm

1
Identify the required NTP operational mode.
The router must act as an NTP client receiving time synchronization from a specified IP address.
The scenario specifies referencing a central time source at 192.168.10.50.
2
Select the appropriate Cisco IOS global configuration command syntax.
The command 'ntp server <ip-address>' establishes the client-server relationship.
'ntp server' is the dedicated Cisco IOS command for designated client NTP synchronization.

Anahtar Kavram

NTP Client Operations and Configuration
Tahmini Süre:45s
Soru 1619Soru →

A Cisco router displays the following output from the command `show ip route`:

text
Gateway of last resort is not set

10.45.12.0/24 is variably subnetted, 4 subnets, 4 masks
O 10.45.12.0/25 [110/20] via 192.168.1.2, 00:14:22, GigabitEthernet0/0
D 10.45.12.64/26 [90/307200] via 192.168.2.2, 00:08:15, GigabitEthernet0/1
S 10.45.12.80/28 [1/0] via 192.168.3.2
O E2 10.45.12.88/30 [110/20] via 192.168.4.2, 00:02:10, GigabitEthernet0/3

The router receives an IP packet with a destination address of 10.45.12.8910.45.12.89. Which next-hop address and exit interface will the router select to forward this packet?

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Cevap: 192.168.4.2 via GigabitEthernet0/3 because the /30 subnet mask provides the longest prefix match for the destination address.

Cevap

The router forwards the packet to next-hop address 192.168.4.2 via interface GigabitEthernet0/3 because 10.45.12.88/30 provides the longest prefix match.
When a router receives a packet, it compares the destination IP address against all entries in the routing table and forwards the packet using the route with the most specific subnet mask (longest prefix match). For destination 10.45.12.89, all four table entries encompass the address, but 10.45.12.88/30 has the longest prefix length (/30), making next-hop 192.168.4.2 via GigabitEthernet0/3 the correct path.

Adım Adım Çözüm

1
Evaluate candidate routes matching destination IP 10.45.12.89
Destination 10.45.12.89 falls into: 10.45.12.0/25 (.0-.127), 10.45.12.64/26 (.64-.127), 10.45.12.80/28 (.80-.95), and 10.45.12.88/30 (.88-.91). All 4 entries are valid candidate routes.
Before selecting a route, the router identifies all entries in the IPv4 routing table whose network boundaries encompass the destination address.
2
Apply Longest Prefix Match (LPM) rule
The prefix lengths are /25, /26, /28, and /30. The /30 route has the most specific mask (longest matching network prefix length of 30 bits).
Routers always prioritize prefix specificity (longest mask length) over Administrative Distance (AD) or metric when determining forwarding decisions.
3
Identify corresponding next-hop and interface
The entry 10.45.12.88/30 specifies next-hop 192.168.4.2 via interface GigabitEthernet0/3.
The forwarding table uses the next-hop IP and outgoing interface tied directly to the winning LPM route.

Anahtar Kavram

Longest Prefix Match (LPM) Rule
Tahmini Süre:1m 15s
Soru 1620Soru →

A non-root switch running Rapid PVST+ receives BPDUs on multiple interfaces with identical path costs to the Root Bridge. Place the tie-breaker criteria in the correct sequential order (from first evaluated to last evaluated) that the switch uses to select its Root Port.

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Cevap

The correct order of evaluation for selecting a Root Port in Rapid PVST+ is: 1) Lowest cumulative root path cost, 2) Lowest sender Bridge ID (BID), 3) Lowest sender port priority, and 4) Lowest sender port number.
When a non-root switch running Rapid PVST+ must select a Root Port from multiple candidate interfaces, it follows a strict four-step tie-breaker sequence: first, it checks for the lowest cumulative root path cost; second, the lowest sender Bridge ID (BID); third, the lowest sender port priority; and fourth, the lowest sender port number (interface ID).

Adım Adım Çözüm

1
Evaluate Root Path Cost
The switch identifies paths with the lowest total cost to reach the Root Bridge.
STP primary objective is forwarding traffic over the shortest cost path.
2
Evaluate Sender Bridge ID
If path costs are equal across multiple candidate ports, compare neighboring switches' BIDs.
Breaks ties when multiple neighboring switches offer equal-cost paths.
3
Evaluate Sender Port Priority
If connected to the same neighbor over multiple links, compare the neighbor's port priority values.
Differentiates multiple links arriving from a single neighboring switch.
4
Evaluate Sender Port Number
If sender port priority values are identical (default 128), select the port connected to the lower sender port number.
Provides a definitive final tie-breaker for parallel connections.

Anahtar Kavram

Rapid PVST+ Root Port Selection Tie-Breaker Sequence
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