Examkin

Network Implementation

424 soru

Tüm türler424Çoktan seçmeli220Çoklu seçim80Sayısal11Eşleştirme53Sıralama42Kısa cevap18
Soru 121Soru →

A network administrator is configuring four interconnected switches running standard IEEE 802.1D Spanning Tree Protocol (STP). All switches currently maintain the default bridge priority value of 32768. Which switch configuration modification will guarantee that a specific switch becomes elected as the STP Root Bridge?

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Cevap: Lower the bridge priority numerical value on the desired switch.

Cevap

Lower the bridge priority numerical value on the desired switch.
In Spanning Tree Protocol (STP), the switch with the lowest numerical Bridge ID (BID) is elected as the Root Bridge. The BID is composed of the Bridge Priority and the switch MAC address. Because all switches default to a priority of 32768, lowering the priority value on a specific switch reduces its BID, ensuring it wins the root election.

Adım Adım Çözüm

1
Identify the criteria used by 802.1D STP for root bridge election.
STP elects the switch with the lowest Bridge ID (BID) as the Root Bridge.
The BID is composed of a 2-byte Bridge Priority followed by a 6-byte MAC Address.
2
Determine how to force a specific switch to have the lowest BID.
Manually lower the Bridge Priority value (e.g., set to 4096 or 0).
Since lower numerical values win the election, reducing the priority below the default 32768 ensures that this switch wins regardless of MAC addresses.

Anahtar Kavram

STP Root Bridge Election and Priority Calibration
Soru 122Soru →

A network administrator is configuring a secondary DNS server to perform a full zone transfer (AXFR) from the primary name server. Which transport layer protocol and port number are used by default to execute this zone transfer?

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Cevap: TCP port 53

Cevap

DNS zone transfers (AXFR/IXFR) use TCP port 53 to guarantee reliable delivery of full or incremental zone database files.
DNS zone transfers (such as AXFR or IXFR) move potentially large amounts of DNS database records between name servers. To guarantee that all resource records arrive intact and in order without data loss, DNS uses TCP port 53 for zone transfers.

Adım Adım Çözüm

1
Identify the type of DNS traffic being requested
The traffic is a zone transfer (AXFR) between a primary and secondary DNS server.
Standard DNS resolution queries use connectionless UDP, but bulk database transfers require reliable session delivery.
2
Determine the transport protocol and port for DNS zone transfers
Zone transfers require TCP on port 53.
TCP ensures packet sequencing, error checking, and reliable retransmission when transferring entire zone records, while port 53 is the dedicated port for DNS services.

Anahtar Kavram

DNS Transport Protocols (UDP 53 for Queries vs TCP 53 for Zone Transfers)
Soru 123Soru →

In what sequential order does a link-state dynamic routing protocol, such as Open Shortest Path First (OSPF), process topology information from initial startup to updating the router's active routing table?

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Cevap

The correct operational sequence begins with discovering neighbors using Hello packets, followed by exchanging Link-State Advertisements (LSAs), building the full Link-State Database (LSDB), executing Dijkstra's Shortest Path First (SPF) algorithm, and finally installing the optimal calculated routes into the IP routing table.
Link-state routing protocols follow a strict, logical lifecycle: discovering neighbors using Hello messages, exchanging link-state information via LSAs, assembling a local copy of the full topology map in the LSDB, running Dijkstra's SPF calculation on that map, and installing the resulting best-path routes into the forwarding table.

Adım Adım Çözüm

1
Identify neighbor discovery
Hello packets are transmitted to locate directly connected neighbor routers.
Link-state routers cannot exchange topology data until neighbor adjacencies are established.
2
Identify topology exchange
Link-State Advertisements (LSAs) are exchanged between adjacent neighbors.
LSAs contain information about connected links, states, and associated path costs.
3
Identify database assembly
The router compiles all received LSAs into a unified Link-State Database (LSDB).
The LSDB serves as the complete topological map of the entire routing area.
4
Identify path computation
Dijkstra's Shortest Path First (SPF) algorithm processes the LSDB topology tree.
SPF calculates the shortest logical path from the local router to every known destination network.
5
Identify route installation
The resulting lowest-cost paths are placed into the active IP routing table.
Only the best calculated paths are selected for active packet forwarding.

Anahtar Kavram

Link-state dynamic routing protocol convergence sequence (OSPF)
Soru 124Soru →

An enterprise network engineer is troubleshooting interconnectivity between two switches, SW-East and SW-West. The switches are connected via a direct fiber link on interface GigabitEthernet1/0/24.

The interface configuration on SW-East is:
text
interface GigabitEthernet1/0/24
switchport mode trunk
switchport trunk native vlan 100
switchport trunk allowed vlan 10,20,30

The interface configuration on SW-West is:
text
interface GigabitEthernet1/0/24
switchport mode trunk
switchport trunk native vlan 100
switchport trunk allowed vlan 10,20,100

Workstations in VLAN 30 connected to SW-East cannot reach resources in VLAN 30 connected to SW-West, while devices on VLAN 10 and VLAN 20 function normally across both switches. System diagnostic logs report no native VLAN mismatch errors.

Which of the following best explains why traffic for VLAN 30 fails to traverse the trunk link?

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Cevap: VLAN 30 is omitted from the allowed VLAN list on SW-West, causing ingress frames tagged with VLAN 30 to be dropped by SW-West.

Cevap

VLAN 30 is omitted from the allowed VLAN list on SW-West, causing ingress frames tagged with VLAN 30 to be dropped by SW-West.
For an 802.1Q trunk to successfully pass traffic for a given VLAN in both directions, that VLAN must be configured in the allowed VLAN list on both switch interfaces. SW-East allows VLAN 30, but SW-West explicitly restricts allowed traffic to VLANs 10, 20, and 100. Consequently, frames tagged with VLAN 30 sent from SW-East are discarded upon ingress at SW-West's interface.

Adım Adım Çözüm

1
Examine the trunk interface configuration on both switches
SW-East allows VLANs 10, 20, and 30. SW-West allows VLANs 10, 20, and 100.
802.1Q trunks only forward frames for VLANs explicitly included in their trunk allowed lists.
2
Trace frame transmission for VLAN 30 from SW-East to SW-West
SW-East inserts an 802.1Q tag for VLAN 30 and transmits the frame across GigabitEthernet1/0/24.
VLAN 30 is not the native VLAN (100), so frames leaving SW-East carry a 4-byte 802.1Q header with VLAN ID 30.
3
Evaluate frame processing upon arrival at SW-West interface GigabitEthernet1/0/24
SW-West checks the allowed VLAN list (10, 20, 100) and drops the VLAN 30 tagged frame.
Since VLAN 30 is missing from SW-West's allowed VLAN list, ingress filtering drops the tagged frame.

Anahtar Kavram

802.1Q Trunk Allowed VLAN List Pruning and Filtering
Tahmini Süre:2m 0s
Soru 125Soru →

An edge routing gateway processes an incoming packet addressed to 10.50.12.9910.50.12.99. The gateway's active routing table contains four operational routes that encompass this destination address:

- Route 1: 10.50.12.96/2910.50.12.96/29 learned via EIGRP (Administrative Distance: 9090, Metric: 2560025600, Next-Hop Interface: eth1)
- Route 2: 10.50.12.96/2810.50.12.96/28 configured as a Static Route (Administrative Distance: 11, Metric: 00, Next-Hop Interface: eth2)
- Route 3: 10.50.12.0/2410.50.12.0/24 learned via OSPF (Administrative Distance: 110110, Metric: 44, Next-Hop Interface: eth3)
- Route 4: 10.50.0.0/1610.50.0.0/16 learned via eBGP (Administrative Distance: 2020, Metric: 1010, Next-Hop Interface: eth4)

Which next-hop interface will the router select to forward this packet, and what is the primary routing rule governing this decision?

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Cevap: The router forwards the packet out eth1 because 10.50.12.96/29 provides the longest prefix match (/29), which takes precedence over administrative distance and metric during route selection.

Cevap

The router selects eth1 as the next-hop interface because 10.50.12.96/29 offers the longest prefix match (/29), which overrides administrative distance and metric considerations.
The correct response identifies eth1 as the next-hop interface because the router evaluates path selection using the Longest Prefix Match (LPM) algorithm first. The destination IP address 10.50.12.99 falls within the subnet range of 10.50.12.96/29 (10.50.12.96 to 10.50.12.103). Because /29 is the longest and most specific subnet mask among all matching routing table entries (/29 vs /28, /24, and /16), the router selects this route immediately without comparing administrative distance or metric values.

Adım Adım Çözüm

1
Determine subnet ranges for all routes matching destination IP 10.50.12.99
10.50.12.96/29 covers 10.50.12.96 to 10.50.12.103. 10.50.12.96/28 covers 10.50.12.96 to 10.50.12.111. 10.50.12.0/24 covers 10.50.12.0 to 10.50.12.255. 10.50.0.0/16 covers 10.50.0.0 to 10.50.255.255. All four routes are valid matches.
The router must identify all matching prefix entries in the forwarding table before applying selection rules.
2
Compare prefix length (subnet mask specificity) across all valid candidate routes
Prefix lengths are /29 (255.255.255.248), /28 (255.255.255.240), /24 (255.255.255.0), and /16 (255.255.0.0).
Longest Prefix Match (LPM) is the absolute first criteria evaluated by an IP routing table lookup.
3
Apply the Longest Prefix Match (LPM) rule to select the forwarding route
The route with the longest prefix mask (/29) associated with next-hop interface eth1 is selected.
Administrative Distance and Metric are only evaluated when breaking ties between identical prefix lengths.

Anahtar Kavram

Longest Prefix Match (LPM) Precedence
Soru 126Soru →

A network technician is configuring an interface on a network switch that connects directly to another switch. The link between the switches must transmit traffic for multiple VLANs across a single physical cable using IEEE 802.1Q tagging. Which interface operational mode should be configured on this port?

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Cevap: Trunk mode

Cevap

Trunk mode
Trunk mode allows a switch interface to carry traffic for multiple VLANs over a single physical link by adding 802.1Q tags to identify frame membership.

Adım Adım Çözüm

1
Identify the connectivity requirement for the inter-switch link.
The single physical connection must carry frames belonging to multiple distinct VLANs.
Switches require a method to identify which VLAN a frame belongs to when sending traffic over a shared inter-switch link.
2
Select the appropriate interface operational mode.
Configuring the interface in trunk mode enables IEEE 802.1Q frame tagging to multiplex multiple VLANs over the link.
Trunk ports apply 802.1Q tags to outgoing frames and read tags on incoming frames, whereas access ports support only one untagged VLAN.

Anahtar Kavram

802.1Q Trunk Interface Configuration
Soru 127Soru →

A network technician is configuring a local interface using the IPv4 subnet block 192.168.50.0/28192.168.50.0/28. What is the maximum number of usable host IP addresses available on this subnet?

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Cevap: 14

Cevap

The maximum number of usable host IP addresses on a /28 subnet is 14.
In IPv4 networking, a /28 prefix reserves 4 bits for host addressing (32−28=432 - 28 = 4). The total number of IP addresses within the block is 24=162^4 = 16. Subtracting the dedicated network address and broadcast address (16−216 - 2) yields 14 usable IP addresses for host devices.

Adım Adım Çözüm

1
Determine the number of host bits in a /28 subnet.
32 total IPv4 bits - 28 network bits = 4 host bits.
The prefix length /28 specifies that 28 bits are reserved for the network prefix.
2
Calculate total available IP addresses.
24=162^4 = 16 total addresses.
The total capacity of a binary address block is 2n2^n, where nn is the number of host bits.
3
Subtract reserved addresses to find usable host count.
16−2=1416 - 2 = 14 usable host IP addresses.
The first address serves as the network identifier and the final address serves as the subnet broadcast address; neither can be assigned to individual hosts.

Anahtar Kavram

IPv4 Subnet Usable Host Calculation
Soru 128Soru →

An edge router receives multiple exterior gateway protocol routes pointing to the same destination network prefix from different autonomous systems. Place the Border Gateway Protocol (BGP) path selection attributes in the correct order of evaluation from first to last.

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Cevap

The correct order of evaluation for BGP path selection attributes from first to last is: Highest Local Preference, Shortest AS-Path length, Lowest Origin type, and Lowest Multi-Exit Discriminator (MED).
BGP path selection follows a deterministic hierarchy to pick the best path when multiple routes exist for a prefix. The evaluation begins with local attributes (Highest Local Preference), proceeds to path metric attributes (Shortest AS-Path length), checks route source reliability (Lowest Origin type), and finally compares entry points for neighboring systems (Lowest MED).

Adım Adım Çözüm

1
Identify the primary outbound policy attribute.
Highest Local Preference is selected as the top criteria evaluated within an Autonomous System.
Local preference takes precedence over path length and origin characteristics to allow local administrators to override default routing decisions.
2
Evaluate path distance metric when local preferences are equal.
Shortest AS-Path length is evaluated second.
BGP prefers routes that cross fewer autonomous systems to minimize inter-domain transit latency.
3
Compare route origin source mechanism.
Lowest Origin type is evaluated third.
Routes created natively via internal routing protocols (IGP) are trusted more than external or unknown redistributed routes.
4
Determine path preference into neighbor autonomous systems.
Lowest Multi-Exit Discriminator (MED) is evaluated fourth.
MED acts as a tie-breaker when multiple entry points exist into the same neighboring autonomous system.

Anahtar Kavram

BGP Path Selection Algorithm Hierarchy
Soru 129Soru →

A core router learns two separate routes to the destination network 192.168.50.0/24192.168.50.0/24 from two different dynamic routing protocols. The first route is learned via Internal EIGRP with an Administrative Distance (AD) of 9090 and a metric cost of 2,176,0002,176,000. The second route is learned via OSPF with an Administrative Distance (AD) of 110110 and a cost metric of 2020. Assuming default settings, which route will the router install into its Routing Information Base (RIB) for traffic destined to 192.168.50.0/24192.168.50.0/24?

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Cevap: The EIGRP route, because lower Administrative Distance takes precedence over protocol metrics when comparing routes from different routing sources.

Cevap

The EIGRP route is installed because lower Administrative Distance takes precedence over protocol metrics when evaluating routes from different sources.
When a router receives multiple routes for the exact same network prefix from different routing protocols, it uses Administrative Distance (AD) to measure administrative trustworthiness. Internal EIGRP defaults to an AD of 90, whereas OSPF defaults to an AD of 110. Because 90 is lower than 110, the router selects the EIGRP path to populate the routing table. Metric comparisons are only performed between paths learned from the exact same dynamic routing protocol.

Adım Adım Çözüm

1
Evaluate destination prefix matching.
Both routes target the exact same prefix length (192.168.50.0/24192.168.50.0/24).
Longest prefix match rule applies first, but since the subnet masks are identical, the router proceeds to compare routing sources.
2
Compare Administrative Distance (AD) values between EIGRP and OSPF.
Internal EIGRP has an AD of 9090, while OSPF has an AD of 110110.
Administrative Distance indicates the trustworthiness of a routing source. Lower values indicate higher believability.
3
Select the route for RIB installation.
The route with AD 9090 (EIGRP) is selected and installed into the routing table.
Because EIGRP has a lower AD than OSPF, the OSPF route is discarded from RIB consideration, making protocol metrics irrelevant during inter-protocol path selection.

Anahtar Kavram

Administrative Distance vs. Routing Metric in Path Selection
Soru 130Soru →

A network administrator connects Switch-A (Root Bridge) to Switch-B using two parallel 10 Gbps Ethernet links for path redundancy. The connections are established as follows:
- Link 1 connects Switch-A port Gi1/0/1 to Switch-B port Gi1/0/1.
- Link 2 connects Switch-A port Gi1/0/2 to Switch-B port Gi1/0/2.

On Switch-A, port Gi1/0/1 uses the default port priority of 128, while port Gi1/0/2 is manually configured with a port priority of 64. On Switch-B, port Gi1/0/1 is manually configured with a port priority of 32, while port Gi1/0/2 retains the default port priority of 128.

Assuming all other Spanning Tree Protocol (STP) parameters remain default and both links are operational, which interface on Switch-B will be selected as the Root Port, and why?

Cevabı ve açıklamayı göster

Cevap: Interface Gi1/0/2, because it receives BPDUs from Switch-A with a lower sender port priority.

Cevap

Interface Gi1/0/2 will be elected as the Root Port on Switch-B because it receives BPDUs containing a lower upstream (Designated) port priority value (64) from Switch-A.
When a non-root switch has multiple equal-cost paths to the Root Bridge originating from the same upstream switch, Root Port selection is determined by evaluating the upstream sender's Port ID (Port Priority + Port Index). Switch-A transmits BPDUs out of Gi1/0/2 with a port priority of 64, which is lower than the default priority of 128 sent out of Gi1/0/1. Switch-B receives this lower value on its Gi1/0/2 interface and selects it as the Root Port.

Adım Adım Çözüm

1
Evaluate the Root Port decision criteria sequence for Switch-B.
Switch-B compares incoming BPDUs on Gi1/0/1 and Gi1/0/2 using the standard STP tie-breaker hierarchy.
Non-root switches must select exactly one Root Port facing the Root Bridge.
2
Compare Root Path Cost and Designated Bridge ID.
Both ports receive BPDUs from the same Root Bridge (Switch-A) over identical 10 Gbps links, resulting in a tie for both criteria.
Both links connect directly between Switch-A and Switch-B at identical speed.
3
Evaluate the Designated (sender) Port ID tie-breaker.
Switch-A transmits BPDUs with Port ID 128.1 on link 1 and Port ID 64.2 on link 2.
Port ID consists of Port Priority + Port Number. Switch-A port Gi1/0/2 advertises a priority of 64, which is lower than 128.
4
Select the Root Port based on lowest Designated Port ID.
Switch-B port Gi1/0/2 receives the BPDU with the lower Designated Port ID (64.2) and becomes the Root Port.
Lower numerical values take precedence in STP decision processes.

Anahtar Kavram

STP Root Port Selection & Designated Sender Port ID Tie-Breakers
Tahmini Süre:1m 30s
Soru 131Soru →

A network administrator needs to configure address translation on an enterprise perimeter router. The network environment requires external users on the internet to reach an internal email server (10.1.1.2510.1.1.25) and an internal web server (10.1.1.5010.1.1.50) using distinct, permanent public IPv4 addresses. Simultaneously, 200200 internal corporate workstations residing on private subnets must be able to access internet resources using a single remaining public IPv4 address. Which combination of translation methods best fulfills these requirements?

Cevabı ve açıklamayı göster

Cevap: Configure Static NAT for both the email and web servers, and Port Address Translation (PAT) for the internal workstations.

Cevap

Configure Static NAT for both the email and web servers, and Port Address Translation (PAT) for the internal workstations.
Static NAT maps a single internal private IP address to a single external public IP address consistently, which is necessary for external hosts to locate and initiate connections to inbound services like web and email servers. Port Address Translation (PAT), also known as NAT Overload, modifies both the source IP address and source port number of outbound traffic, permitting multiple private host IP addresses to share a single public IPv4 address efficiently.

Adım Adım Çözüm

1
Analyze server accessibility requirements.
Inbound connections from the internet to internal servers require persistent, dedicated public IP mappings.
Static NAT creates a fixed one-to-one translation between a specific private Inside Local IP address and a public Inside Global IP address.
2
Analyze workstation outbound internet requirements.
200 workstations must share a single public IP address.
Port Address Translation (PAT / NAT Overload) tracks outbound connections using unique transport layer source port numbers, allowing many internal hosts to share one public IP address.
3
Combine translation methods.
Static NAT for the two servers plus PAT for the workstations meets all criteria.
This setup conserves public IPv4 addresses while maintaining full inbound accessibility for hosted services.

Anahtar Kavram

Static NAT vs. Port Address Translation (PAT/Overload) implementation criteria
Soru 132Soru →

A network technician is configuring an 802.1Q trunk link between two switches to carry traffic across multiple VLANs. Which VLAN designation is assigned to handle untagged frame traffic traversing this trunk by default?

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Cevap: Native VLAN

Cevap

Native VLAN
In 802.1Q trunking, the native VLAN is explicitly designated to forward untagged traffic received on or sent across a trunk port without inserting an 802.1Q VLAN tag.

Adım Adım Çözüm

1
Identify the operation of 802.1Q trunking.
802.1Q trunking adds a 4-byte header tag to frames belonging to specific VLANs to distinguish them across switches.
Trunk links carry traffic for multiple VLANs over a single physical link.
2
Determine how untagged frames are handled on a trunk link.
Untagged frames do not contain an 802.1Q header tag and are mapped directly to the designated native VLAN.
By default, 802.1Q encapsulation defines a native VLAN to support backward compatibility and untagged legacy traffic.

Anahtar Kavram

802.1Q Native VLAN Operation
Soru 133Soru →

When a router receives an IP packet, it compares the destination address against multiple matching entries in its routing table. In what sequence does the router evaluate these routing criteria to select the single best path for forwarding?

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Cevap

The correct order of route selection evaluation is: 1. Longest Prefix Match, 2. Lowest Administrative Distance, 3. Lowest Metric.
Routers follow a strict hierarchy to determine the best path. First, the router checks for the longest prefix match to find the most specific network destination. If multiple candidate routes share the exact same prefix length, the router compares administrative distance to select the most reliable routing source. Finally, if routes originate from the same protocol and prefix length, the router uses the metric to break the tie.

Adım Adım Çözüm

1
Evaluate subnet mask specificity
The router selects the entry with the longest network prefix (most specific subnet mask).
Longest prefix match always takes precedence over administrative distance and metrics.
2
Compare administrative distance if prefix lengths are equal
The router selects the route coming from the source with the lower administrative distance.
Administrative distance measures the trustworthiness of the routing protocol or static route source.
3
Compare routing metric if route sources are identical
The router selects the path with the lowest metric value (e.g., hop count, cost, or bandwidth).
Metric is used to compare multiple paths learned within the exact same dynamic routing protocol.

Anahtar Kavram

Route Selection Order of Precedence
Soru 134Soru →

Match each VLAN configuration or 802.1Q trunking component on the left with its correct operational description on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Access Port
Trunk Port
Native VLAN
802.1Q Header

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Access Port matches 'Carries traffic for a single assigned VLAN and connects directly to end-user devices.', Trunk Port matches 'Carries traffic for multiple VLANs across a single physical link using frame encapsulation.', Native VLAN matches 'Transmits and receives untagged frame traffic across an 802.1Q trunk link.', and 802.1Q Header matches 'Inserts a 4-byte field into the Ethernet frame containing a 12-bit VLAN ID (VID)'.
Each VLAN term corresponds directly to its standard IEEE 802.1Q definition: Access ports connect single-VLAN end devices, trunk ports transport multi-VLAN traffic across switches, native VLANs process untagged frames on a trunk, and 802.1Q headers insert 4 bytes of tagging information containing the VLAN ID.

Adım Adım Çözüm

1
Identify the role of an Access Port
Connects end-user devices and carries traffic for only one assigned VLAN.
Access ports strip tags before forwarding traffic to host endpoints.
2
Identify the role of a Trunk Port
Carries traffic from multiple VLANs between switches or switches and routers.
Trunks allow multiple logical networks to share a single physical cabling interface.
3
Identify the purpose of the Native VLAN
Manages untagged frame transmission over 802.1Q trunk connections.
By default, 802.1Q trunk links process untagged frames on the assigned native VLAN.
4
Identify the function of the 802.1Q Header
Inserts a 4-byte tag into the Ethernet frame specifying the 12-bit VLAN ID.
Frame tagging allows receiving switch ports to identify which VLAN the frame belongs to.

Anahtar Kavram

VLAN Trunking and 802.1Q Tagging Basics
Soru 135Soru →

A network administrator is configuring an 802.1Q trunk connection between two switches. Devices on tagged VLANs communicate normally across the link, but untagged traffic sent from one switch arrives on an unexpected VLAN on the opposite switch. Which misconfiguration is the primary cause of this issue?

Cevabı ve açıklamayı göster

Cevap: A native VLAN mismatch exists between the trunk interfaces on the two switches.

Cevap

A native VLAN mismatch exists between the trunk interfaces on the two switches.
The correct answer correctly identifies a native VLAN mismatch. Under the IEEE 802.1Q trunking specification, untagged frames transmitted across a trunk link belong to the sending switch's native VLAN. When received, the neighboring switch assigns those untagged frames to its own configured native VLAN. If these VLAN IDs differ between switches, traffic leaks from one VLAN into another without routing.

Adım Adım Çözüm

1
Analyze trunk traffic behavior
Tagged traffic passes correctly, but untagged traffic is received on an unexpected VLAN.
802.1Q trunks transport tagged frames with an explicit 4-byte VLAN tag header, while untagged frames are implicitly assigned to the native VLAN configured on the receiving interface.
2
Identify the role of the Native VLAN
Recognize that mismatched native VLAN configurations cause untagged frame leakage.
If Switch-1 uses Native VLAN 10 and Switch-2 uses Native VLAN 20, untagged frames sent by Switch-1 will be interpreted as VLAN 20 traffic upon arrival at Switch-2.

Anahtar Kavram

802.1Q Native VLAN Operation
Tahmini Süre:45s
Soru 136Soru →

A network administrator is inspecting an 802.1Q trunk link configured between Switch-A and Switch-B. Interface GigabitEthernet0/1 on Switch-A is configured with `switchport trunk native vlan 10`. On Switch-B, interface GigabitEthernet0/1 is configured with `switchport trunk native vlan 50`. When Switch-A transmits untagged Ethernet frames across this link to Switch-B, which of the following outcomes will occur?

Cevabı ve açıklamayı göster

Cevap: Switch-B will accept the untagged frames and associate them with VLAN 50.

Cevap

Switch-B will accept the untagged frames and associate them with VLAN 50.
Under 802.1Q trunking, traffic belonging to the configured native VLAN is sent untagged across the link. Switch-A sends VLAN 10 traffic untagged because VLAN 10 is its native VLAN. Switch-B receives the untagged traffic and assigns it to its own local native VLAN, which is VLAN 50. This results in untagged frames leaking from VLAN 10 on Switch-A into VLAN 50 on Switch-B.

Adım Adım Çözüm

1
Determine frame transmission behavior on Switch-A
Frames belonging to VLAN 10 on Switch-A match its native VLAN setting (`vlan 10`). Consequently, Switch-A transmits these frames across the 802.1Q trunk link without an explicit 4-byte 802.1Q header tag.
802.1Q trunking specifies that frames on the native VLAN are forwarded untagged.
2
Determine frame reception behavior on Switch-B
Switch-B receives untagged frames on interface GigabitEthernet0/1. Switch-B checks its local port configuration, identifies its native VLAN as VLAN 50, and places the incoming untagged traffic into VLAN 50.
Switches place all untagged ingress frames on an 802.1Q trunk port into the native VLAN configured on that local port.
3
Evaluate the net impact of the configuration
Traffic originating on VLAN 10 on Switch-A improperly leaks into VLAN 50 on Switch-B, creating a security issue and native VLAN mismatch condition.
Mismatched native VLAN IDs across a trunk link cause untagged frame cross-talk between different VLANs.

Anahtar Kavram

802.1Q Native VLAN Untagged Frame Processing and Mismatch Behavior
Soru 137Soru →

A network engineer is provisioning switch interface profiles across an enterprise network that includes desktop workstations, IP phones, and inter-switch links. Match each switchport configuration command on the left with its corresponding operational frame behavior on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

switchport mode access
switchport trunk native vlan 50
switchport trunk allowed vlan 10,20
switchport voice vlan 30

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Matching pairs: 'switchport mode access' pairs with single broadcast domain untagged handling; 'switchport trunk native vlan 50' pairs with untagged frame processing for specified ID on 802.1Q trunk; 'switchport trunk allowed vlan 10,20' pairs with restricting trunk traffic to permitted tagged VLAN IDs; 'switchport voice vlan 30' pairs with processing untagged data traffic alongside tagged IP telephony traffic.
Each switchport parameter maps directly to its 802.1Q framing specification: access ports strip headers for single VLAN endpoints, native VLAN commands dictate which trunk traffic remains untagged, allowed lists control 802.1Q tag filtering, and voice VLAN allows simultaneous tagged voice and untagged data traffic.

Adım Adım Çözüm

1
Analyze standard access port behavior.
Identified that access ports belong to one VLAN and do not retain 802.1Q tags when delivering frames to endpoint devices.
Endpoint devices such as standard PCs expect untagged Ethernet II frames.
2
Analyze 802.1Q native VLAN operation.
Matched native VLAN configuration to the rule specifying untagged frame transmission/reception across an 802.1Q trunk.
By default in 802.1Q, one VLAN per trunk is designated to carry untagged frames to maintain backward compatibility.
3
Analyze allowed VLAN list configuration.
Associated the allowed VLAN statement with frame filtering that limits trunk traversal to explicitly permitted VLAN IDs.
Trunk pruning and security filtering restrict broadcast domains from spanning unnecessary switch links.
4
Analyze voice VLAN port behavior.
Linked auxiliary voice VLAN setup to multi-VLAN access port operation handling untagged PC data and tagged voice traffic.
IP phones act as mini-switches, tagging their own VoIP traffic while bridging untagged workstation frames.

Anahtar Kavram

802.1Q VLAN Frame Identification and Port Modes
Soru 138Soru →

A network administrator is reviewing a router's configuration where both a static route and an OSPF dynamic routing protocol offer paths to the exact same destination subnet. Which attribute does the router evaluate first to determine which routing source is more trustworthy and should be installed into the active routing table?

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Cevap: Administrative distance

Cevap

Administrative distance is evaluated first when comparing routes to the same destination from different routing protocols or static configuration.
Administrative distance measures the trustworthiness of a routing information source. When a router receives route information for an identical destination prefix from different sources, it selects the source with the lowest administrative distance to populate the active routing table.

Adım Adım Çözüm

1
Identify the routing sources competing for entry in the routing table.
The router has learned paths to the same destination via both static routing and OSPF dynamic routing.
When multiple sources provide routes to identical destination networks, a selection tie-breaker mechanism is required.
2
Determine the primary criterion used to rate protocol trustworthiness.
Administrative Distance (AD) assigns a numerical believability rating to each routing source (e.g., Static = 1, OSPF = 110).
Lower Administrative Distance values take precedence over higher values before internal protocol metrics are considered.

Anahtar Kavram

Administrative Distance vs. Metric in Route Selection
Tahmini Süre:45s
Soru 139Soru →

An enterprise network engineer is provisioning a switch interface connecting switch SW-Floor3 to the distribution switch SW-Dist1. The link carries traffic for VLAN 10 (Corporate Data), VLAN 20 (Guest Wi-Fi), and VLAN 50 (VoIP Telephony). IP phones connected to SW-Floor3 fail to register with the central call manager on VLAN 50, although workstations on VLAN 10 communicate across the link normally.

The engineer views the trunk configuration on interface GigabitEthernet1/0/48:
text
interface GigabitEthernet1/0/48
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk native vlan 10
switchport trunk allowed vlan 10,20,30

Which of the following identifies the root cause of the VoIP communication failure?

Cevabı ve açıklamayı göster

Cevap: The allowed VLAN pruning list on the trunk interface omits VLAN 50, preventing traffic belonging to the voice network from traversing the link.

Cevap

The allowed VLAN pruning list on the trunk interface omits VLAN 50, preventing traffic belonging to the voice network from traversing the link.
The configuration command 'switchport trunk allowed vlan 10,20,30' creates an explicit permit list for trunking. Because VLAN 50 is not included in this allowed list, the switch prunes VLAN 50 traffic, dropping all ingress and egress 802.1Q tagged frames associated with the voice network on this port.

Adım Adım Çözüm

1
Analyze the reported symptom and requirements.
Workstations on VLAN 10 work normally across the trunk, but IP phones on VLAN 50 cannot communicate with the call manager.
This indicates a selective VLAN transmission issue over the physical trunk link GigabitEthernet1/0/48.
2
Examine the interface CLI configuration snippet.
The command 'switchport trunk allowed vlan 10,20,30' restricts traffic on GigabitEthernet1/0/48 exclusively to VLANs 10, 20, and 30.
By explicitly specifying an allowed VLAN list without including VLAN 50, any frames carrying an 802.1Q tag for VLAN 50 are dropped at the interface.
3
Determine the necessary remediation.
VLAN 50 must be appended to the allowed VLAN list on the trunk interface.
Adding VLAN 50 enables 802.1Q tagged frames for the voice network to traverse the trunk link between switches.

Anahtar Kavram

802.1Q Trunk Allowed VLAN Filtering
Soru 140Soru →

Which of the following are key operational characteristics of link-state dynamic routing protocols, such as OSPF? (Select TWO)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Routers construct a full topology map of the network area to calculate optimal paths.; Updates are sent as triggered link-state updates when topology changes occur rather than on strict full-table timers.

Cevap

The correct characteristics are that routers construct a full topology map of the network area to calculate optimal paths, and that updates are sent as triggered link-state updates when topology changes occur.
Link-state dynamic routing protocols maintain full network visibility by constructing a topology database of the area. Additionally, they conserve bandwidth and achieve faster convergence by dispatching triggered LSA updates when link states change instead of constantly broadcasting full routing tables.

Adım Adım Çözüm

1
Identify the core mechanics of link-state routing protocols (e.g., OSPF).
Link-state protocols rely on all routers sharing link status information to maintain a synchronized map of the network topology and compute shortest path trees.
Understanding the fundamental differences between link-state and distance-vector protocol updates is critical for evaluating routing protocol behavior.
2
Evaluate update mechanisms for link-state protocols.
Link-state updates are event-driven and triggered upon network changes rather than sending periodic full-table dumps.
Triggered incremental updates reduce bandwidth consumption and improve network convergence speed.
3
Differentiate Layer 3 dynamic routing from Layer 2 switching and NAT services.
Dynamic routing protocols function at Layer 3 to determine paths between networks, distinct from Layer 2 switching or NAT/PAT translation services.
Distinguishing protocol layers and operational scopes prevents confusing routing mechanisms with address translation or switching mechanisms.

Anahtar Kavram

Link-State Dynamic Routing Protocol Behavior
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