Network Implementation

424 soru

Tüm türler424 Çoktan seçmeli220 Çoklu seçim80 Sayısal11 Eşleştirme53 Sıralama42 Kısa cevap18

A network architect is implementing specialized DNS configurations across an enterprise hybrid cloud environment. Match each operational requirement on the left with its corresponding DNS resource record type on the right.

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Cevap

Dynamic service discovery with port/protocol parameters maps to SRV Record; email security and cryptographic key publishing maps to TXT Record; IP address to FQDN reverse lookups map to PTR Record; zone authority and synchronization timing metadata map to SOA Record.

Each requirement aligns with the specific functional specification of the corresponding DNS record type: SRV enables port/protocol service discovery, TXT provides text key storage for DKIM/SPF, PTR provides IP-to-FQDN reverse resolution, and SOA governs zone authority and replication timers.

Adım Adım Çözüm

Analyze service location requirements

Dynamic location of network services requiring specific port numbers, transport protocols, priorities, and weights strictly mandates an SRV record.

Standard host records (A/AAAA/CNAME) do not store protocol or port configuration details.

Analyze email security authentication specifications

Storing public keys (DKIM) and SPF policy statements requires a TXT record.

TXT records provide text payload storage designed for security authentication policies without requiring dedicated custom record types.

Analyze reverse IP lookup requirements

Mapping an IP address back to its associated FQDN requires a PTR record.

PTR records populate the reverse lookup zone structure (in-addr.arpa / ip6.arpa) specifically used for security validation and logging.

Analyze zone administrative parameter requirements

Defining primary name server authority, contact email, serial number, and secondary server refresh timers mandates an SOA record.

Every valid DNS zone must contain exactly one SOA record at the apex to govern zone replication and administrative parameters.

Anahtar Kavram

DNS Infrastructure and Resource Record Functionality

Tahmini Süre:2m 0s

Soru 382Soru →

A network architect is designing an IPv4 subnetting plan for a new high-availability database cluster. The cluster requires IP assignments for 28 database server nodes, 1 dedicated out-of-band monitoring probe, 1 management appliance, and a redundant default gateway deployment using HSRP (which requires 2 physical interface IP addresses and 1 Virtual IP address). Furthermore, enterprise policy dictates that the provisioned subnet must accommodate at least a 25% growth headroom above the total initial IP requirements. Which CIDR prefix length represents the most efficient (smallest) IPv4 subnet that satisfies all requirements, and how many usable host IP addresses will remain unassigned after the initial deployment?

/26 prefix length with 29 remaining usable host IP addresses

/26 prefix length with 31 remaining usable host IP addresses

/27 prefix length with 0 remaining usable host IP addresses

/25 prefix length with 93 remaining usable host IP addresses

Cevabı ve açıklamayı göster

Cevap: /26 prefix length with 29 remaining usable host IP addresses

Cevap

The most efficient subnet is a /26 prefix length, which leaves 29 remaining usable host IP addresses.

The total required IP count for the deployment is 33 (28 database nodes + 1 probe + 1 appliance + 3 HSRP gateway addresses). Adding 25% headroom requires supporting at least 42 usable IP addresses. A /26 subnet yields

2^6 - 2 = 62

usable host IP addresses, which is the smallest subnet that accommodates at least 42 hosts. Subtracting the initial 33 assigned addresses leaves 29 unassigned usable host IPs.

Adım Adım Çözüm

Calculate the total initial host IP requirement

28 (servers) + 1 (probe) + 1 (appliance) + 2 (HSRP physical interfaces) + 1 (HSRP VIP) = 33 required IP addresses.

Redundant gateway protocols such as HSRP require individual IP addresses for each physical router interface plus a shared Virtual IP.

Apply the 25% growth headroom expansion requirement

33 × 1.25 = 41.25, which rounds up to a minimum required capacity of 42 usable host IP addresses.

Network design specifications require provisioned subnets to accommodate growth beyond initial deployment counts.

Determine the smallest CIDR prefix length supporting at least 42 usable host IPs

A /27 subnet provides

2^{(32-27)} - 2 = 30

usable host IPs (insufficient). A /26 subnet provides

2^{(32-26)} - 2 = 62

usable host IPs (sufficient).

Subnet host capacity is calculated using the formula

2^h - 2

, where

h

is the number of host bits remaining.

Calculate unassigned remaining usable host IP addresses

62 usable IPs - 33 assigned IPs = 29 remaining usable host IP addresses.

Subtracting the initial deployment count from total usable capacity yields remaining capacity for growth.

Anahtar Kavram

IPv4 Subnet Mask Calculation and Usable Host Address Estimation

Tahmini Süre:3m 0s

Soru 383Soru →

A network technician is configuring a dedicated VLAN for a department that requires $30$ desktop computers and $1$ IP phone, requiring a total of $31$ usable host IPv4 addresses. Which subnet mask is the most efficient choice that fulfills this requirement without wasting unnecessary address space?

255.255.255.192

255.255.255.224

255.255.255.240

255.255.255.128

Cevabı ve açıklamayı göster

Cevap: 255.255.255.192

Cevap

255.255.255.192

To host

31

devices, the subnet must offer at least

31

usable host IP addresses. The formula for usable IPs is

2^n - 2

, where

n

represents host bits. A /27 subnet (

255.255.255.224

) provides

2^5 - 2 = 30

usable IPs, which is one address short. Therefore, the next larger subnet size is required, which is /26 (

255.255.255.192

), giving

2^6 - 2 = 62

usable host IPs.

Adım Adım Çözüm

Calculate total host IP addresses required including host overhead.

31 usable IP addresses are required.

The subnet must support 30 computers and 1 IP phone (30 + 1 = 31).

Apply the usable host capacity formula

2^n - 2 \ge H

, where

n

is the number of host bits and

H

is the required usable host count.

For

n=5

2^5 - 2 = 30

usable addresses (insufficient). For

n=6

2^6 - 2 = 62

usable addresses (sufficient).

Two addresses in every subnet must be reserved for the network ID and the directed broadcast address.

Determine the prefix length and dotted-decimal subnet mask corresponding to

6

host bits.

Prefix length is

32 - 6 = /26

. The decimal mask is

255.255.255.192

A prefix of /26 leaves 6 bits for hosts (

255.255.255.11000000_2 = 255.255.255.192

Anahtar Kavram

IPv4 Usable Host Count Calculation

Tahmini Süre:1m 30s

Soru 384Soru →

A network operations team deploys a new trunk link between access switch SW-Acc-02 and core switch SW-Core-01. Users connected to ports assigned to VLAN 20 on SW-Acc-02 report that they cannot reach servers on VLAN 20 located behind SW-Core-01, while users on VLAN 10 experience normal connectivity.

The current interface configurations are shown below:

SW-Acc-02 Interface Configuration:
text
interface GigabitEthernet1/0/48
switchport mode trunk
switchport trunk native vlan 99
switchport trunk allowed vlan 10,99

SW-Core-01 Interface Configuration:
text
interface GigabitEthernet0/24
switchport mode trunk
switchport trunk native vlan 99
switchport trunk allowed vlan 10,20,99

Which configuration change on SW-Acc-02 will resolve the loss of connectivity for VLAN 20 traffic across the trunk?

Add VLAN 20 to the switchport trunk allowed vlan list on interface GigabitEthernet1/0/48.

Change the native VLAN on interface GigabitEthernet1/0/48 from VLAN 99 to VLAN 20.

Enable IP routing process on SW-Acc-02 to route VLAN 20 traffic across the trunk.

Reconfigure interface GigabitEthernet1/0/48 as a static access port assigned to VLAN 20.

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Cevap: Add VLAN 20 to the switchport trunk allowed vlan list on interface GigabitEthernet1/0/48.

Cevap

Add VLAN 20 to the switchport trunk allowed vlan list on interface GigabitEthernet1/0/48.

The correct answer adds VLAN 20 to the allowed list on SW-Acc-02. An 802.1Q trunk interface only forwards and receives traffic for VLANs specified in its allowed VLAN list. Because SW-Acc-02 was configured to allow only VLANs 10 and 99, all frames for VLAN 20 were dropped at the ingress/egress interface GigabitEthernet1/0/48.

Adım Adım Çözüm

Analyze the trunk configuration on SW-Acc-02.

Interface GigabitEthernet1/0/48 is configured with 'switchport trunk allowed vlan 10,99', which restricts trunk traffic exclusively to VLAN 10 and VLAN 99.

By default, trunks allow all VLANs unless explicitly filtered using the allowed VLAN list command.

Compare SW-Acc-02 allowed VLAN list with SW-Core-01 configuration.

SW-Core-01 allows VLAN 10, 20, and 99, but SW-Acc-02 drops incoming and outgoing VLAN 20 tagged frames at interface GigabitEthernet1/0/48 due to the restrictive allowed list.

802.1Q trunks drop frames tagged with VLAN IDs that are not explicitly included in their allowed VLAN filter.

Determine the necessary remediation command.

Executing 'switchport trunk allowed vlan add 20' or modifying the allowed list to '10,20,99' on SW-Acc-02 allows VLAN 20 frames to traverse the trunk link.

Both switches at the ends of an 802.1Q trunk must explicitly permit the VLANs intended to cross the inter-switch link.

Anahtar Kavram

802.1Q Trunk Allowed VLAN List Pruning and Filtering

Tahmini Süre:1m 30s

Soru 385Soru →

A network administrator configures an IEEE 802.1Q trunk interface on a switch and executes the command `switchport trunk native vlan 20`. How does the switch handle outgoing frames belonging to VLAN 20 on this trunk interface?

It transmits the frames onto the link without adding an 802.1Q VLAN tag.

It encapsulates the frames with an 802.1Q header containing VLAN ID 20.

It drops the frames because native VLAN traffic cannot travel across a trunk link.

It routes the frames directly to VLAN 1 without requiring a Layer 3 device.

Cevabı ve açıklamayı göster

Cevap: It transmits the frames onto the link without adding an 802.1Q VLAN tag.

Cevap

It transmits the frames onto the link without adding an 802.1Q VLAN tag.

On an IEEE 802.1Q trunk port, traffic belonging to the designated native VLAN is transmitted across the link without an added 802.1Q header tag. Because VLAN 20 is configured as the native VLAN, outgoing frames for VLAN 20 are sent untagged.

Adım Adım Çözüm

Identify the operation of IEEE 802.1Q native VLANs on trunk interfaces.

IEEE 802.1Q defines a native VLAN for trunk links where traffic is forwarded without an 802.1Q header tag.

Native VLAN configuration allows untagged frame transmission across trunk links for backward compatibility with non-tagging devices.

Apply the configuration command to VLAN 20.

Frames associated with VLAN 20 on this specific port will be egressed untagged.

The command explicitly sets VLAN 20 as the native VLAN for the trunk port.

Anahtar Kavram

802.1Q Native VLAN Tagging Behavior

Soru 386Soru →

A network engineer is selecting a dynamic routing protocol for an enterprise internal network that incorporates routers from multiple hardware vendors. The network architecture requires an open-standard Interior Gateway Protocol (IGP) that uses link-state technology, supports hierarchical organization through area partitioning to constrain link-state advertisement propagation, and utilizes Dijkstra's algorithm for path determination. Which dynamic routing protocol best satisfies all of these requirements?

Open Shortest Path First (OSPF)

Border Gateway Protocol (BGP)

Enhanced Interior Gateway Routing Protocol (EIGRP)

Routing Information Protocol version 2 (RIPv2)

Cevabı ve açıklamayı göster

Cevap: Open Shortest Path First (OSPF)

Cevap

Open Shortest Path First (OSPF) is the correct dynamic routing protocol because it is an open-standard link-state IGP that uses area hierarchies and Dijkstra's Shortest Path First algorithm.

Open Shortest Path First (OSPF) satisfies all criteria: it is an open-standard IGP, uses a link-state architecture with an area hierarchy (Area 0 backbone and non-backbone areas), and runs Dijkstra's Shortest Path First algorithm to compute optimal routes.

Adım Adım Çözüm

Identify the protocol scope required by the scenario

The requirement specifies an Interior Gateway Protocol (IGP) for internal network routing across multi-vendor equipment.

Exterior gateway protocols like BGP handle inter-autonomous system routing, while IGPs handle intra-autonomous system routing.

Evaluate the underlying routing algorithm and architectural model

The scenario requires link-state protocol architecture, hierarchical area structures, and Dijkstra's algorithm execution.

OSPF maintains full link-state databases (LSDB) within areas and runs Dijkstra's Shortest Path First (SPF) algorithm to calculate loop-free paths.

Verify open-standard interoperability across multi-vendor devices

OSPF is fully defined by open IETF standards (RFC 2328), ensuring compatibility across all networking vendor equipment.

Open standards guarantee seamless interoperability in heterogeneous environments.

Anahtar Kavram

Link-State Dynamic Routing Protocols and OSPF Characteristics

Tahmini Süre:1m 30s

Soru 387Soru →

A network administrator is reviewing dynamic routing protocol operational characteristics during an enterprise network redesign. Which of the following statements correctly compare link-state and distance-vector routing protocols? (Select TWO.)

Geçerli olan tümünü seçin

Link-state protocols maintain a full network topology map by exchanging link-state updates, whereas distance-vector protocols pass full or partial routing tables only to directly connected neighbors.

Distance-vector protocols operate strictly at Layer 2 to evaluate physical frame delivery, whereas link-state protocols operate strictly at Layer 4 by mapping TCP port connections.

Link-state protocols typically achieve faster network convergence than distance-vector protocols because each router independently computes optimal paths using Dijkstra's Shortest Path First algorithm.

Distance-vector protocols require Port Address Translation (PAT) to multiplex routing update packets across single public IP addresses at every hop.

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Cevap: Link-state protocols maintain a full network topology map by exchanging link-state updates, whereas distance-vector protocols pass full or partial routing tables only to directly connected neighbors.; Link-state protocols typically achieve faster network convergence than distance-vector protocols because each router independently computes optimal paths using Dijkstra's Shortest Path First algorithm.

Cevap

Link-state protocols maintain a full network topology map by exchanging link-state updates while distance-vector protocols pass routing information only to directly connected neighbors, and link-state protocols converge faster because routers independently run Dijkstra's algorithm.

Link-state protocols (e.g., OSPF) exchange link status information to build a comprehensive map of the entire network topology and run Dijkstra's algorithm to converge rapidly when link states change. Distance-vector protocols (e.g., RIP) exchange routing tables directly with connected neighbors and process updates sequentially, resulting in slower convergence.

Adım Adım Çözüm

Analyze how topology awareness differs between protocol types.

Link-state protocols maintain a full topology map of the area (via LSAs), while distance-vector protocols rely on neighbor-provided routing tables (routing by rumor).

This is a fundamental architectural distinction between link-state and distance-vector protocol operation.

Analyze convergence mechanisms and calculation methods.

Link-state protocols react rapidly to state changes by recalculating paths using the Dijkstra Shortest Path First algorithm on local topology maps, achieving faster convergence.

Independent local calculation leads to significantly faster convergence than distance-vector hop-by-hop convergence mechanisms.

Evaluate OSI layer and NAT/PAT claims in the distractors.

Dynamic routing protocols evaluate Layer 3 logical network paths; they do not operate at Layer 2/Layer 4 frame/port headers or depend on Port Address Translation.

Routing protocols govern Layer 3 IP path selection.

Anahtar Kavram

Link-State vs. Distance-Vector Dynamic Routing Characteristics

Soru 388Soru →

A router's IP routing table contains four active paths capable of reaching the IP address $10.1.4.10$ :

Prefix / Subnet	Routing Protocol	Administrative Distance
$10.1.0.0/16$	OSPF	$110$
$10.1.4.0/24$	EIGRP	$90$
$10.1.4.0/28$	RIPv2	$120$
$0.0.0.0/0$	Static Route	$1$

When a frame containing a packet destined for $10.1.4.10$ arrives at the router, which route will be selected to forward the packet?

The RIPv2 route (

10.1.4.0/28

), because the longest prefix match is evaluated before administrative distance.

The static route (

0.0.0.0/0

), because static routes have the lowest administrative distance value.

The EIGRP route (

10.1.4.0/24

), because EIGRP has a lower administrative distance than OSPF and RIP for matching networks.

The OSPF route (

10.1.0.0/16

), because link-state protocols take priority over distance-vector protocols during packet forwarding.

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Cevap: The RIPv2 route ( $10.1.4.0/28$ ), because the longest prefix match is evaluated before administrative distance.

Cevap

The router selects the RIPv2 route (

10.1.4.0/28

) because the longest prefix match (LPM) rule dictates that the route with the most specific subnet mask matching the destination IP address is always selected first.

When a router receives a packet, it performs a lookup in its forwarding table and prioritizes routes based on Longest Prefix Match (LPM). The route with the narrowest host range (longest network prefix mask length) matching the destination IP address is selected regardless of administrative distance or protocol metric. In this scenario,

10.1.4.0/28

has 28 matching network bits, which is longer than

/24

/16

, or

/0

Adım Adım Çözüm

Determine which routes in the table match the destination address

10.1.4.10

All four routes (

10.1.0.0/16

10.1.4.0/24

10.1.4.0/28

, and

0.0.0.0/0

) enclose the IP address

10.1.4.10

Any route encompassing the IP subnet ranges can technically handle the traffic.

Compare prefix lengths (subnet mask bits) among matching candidate routes.

The prefix lengths are

/28

(28 bits),

/24

(24 bits),

/16

(16 bits), and

/0

(0 bits).

The longest prefix match (LPM) decision rule mandates that the most specific matching prefix (highest prefix mask length) is chosen prior to evaluating Administrative Distance or Metric.

Select the route with the longest prefix match.

The

/28

prefix (

10.1.4.0/28

learned via RIPv2) is chosen as the forwarding entry.

Because

/28

is the longest matching subnet mask, Administrative Distance is not evaluated across the differing prefix lengths.

Anahtar Kavram

Longest Prefix Match (LPM) Rule

Tahmini Süre:1m 0s

Soru 389Soru →

A core router receives a packet destined for a remote subnet and must select the best path from multiple overlapping entries in its routing database. Place the decision criteria in the exact sequence the routing logic applies them to determine the single active forwarding path.

Öğeleri doğru sıraya koymak için sürükleyin

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Cevap

The router first evaluates the longest prefix match to narrow candidate routes. If multiple routes match the same prefix length, it evaluates Administrative Distance to select the most trustworthy protocol. If routes originate from the same protocol with equal AD, it uses the metric to break the tie, and finally installs the path or enables ECMP load balancing.

The proper decision path evaluation sequence starts with Longest Prefix Match (prefix specificity), followed by Administrative Distance (protocol believability), then internal protocol metric (path cost), culminating in forwarding path installation or load balancing.

Adım Adım Çözüm

Evaluate subnet mask prefix length

Candidate routes are narrowed to those with the most specific prefix matching the destination IP.

Prefix length takes absolute precedence over protocol trustworthiness or metric values.

Evaluate Administrative Distance

The route with the lowest AD is selected among matching routes with identical prefix lengths.

Administrative distance rates the believability of different routing sources (e.g., OSPF vs. RIP).

Evaluate protocol metric cost

The route with the lowest metric cost is chosen if multiple routes come from the same routing protocol.

Metrics are internal values (like hop count or bandwidth cost) used to rank paths within a single protocol instance.

Perform FIB installation or ECMP

The single best route is active in the FIB, or traffic is load-balanced across equal-cost paths.

This is the final operational phase of path selection before packet transmission.

Anahtar Kavram

IP Route Selection Decision Process

Soru 390Soru →

A network administrator is configuring a interface on a syslog server with the IPv4 address $192.168.45.138/26$ . What is the network ID (subnet address) of the subnetwork to which this server belongs?

Cevabı ve açıklamayı göster

Cevap: 192.168.45.128; 192.168.45.128/26

Cevap

192.168.45.128

With a

/26

prefix, the subnet mask is

255.255.255.192

. The block size in the fourth octet is

256 - 192 = 64

. Subnets in this range start at

.0

.64

.128

, and

.192

. Since the host address fourth octet is

138

, it resides within the

192.168.45.128/26

subnet (covering addresses

192.168.45.128

through

192.168.45.191

). The network ID is

192.168.45.128

Adım Adım Çözüm

Determine the subnet mask block size from the CIDR prefix length.

/26

prefix leaves

32 - 26 = 6

host bits in the fourth octet. The block size (increment value) is

2^6 = 64

Knowing the block size allows identification of the subnet boundaries in the relevant octet.

Calculate the subnet boundaries in the fourth octet.

The fourth octet subnet ranges start at increments of

64

.0

.64

.128

, and

.192

Subnet IDs always begin on multiples of the block size starting from 0.

Locate the range containing the host IP fourth octet (

138

The fourth octet value

138

falls between

128

and

191

. Therefore, the network ID is

192.168.45.128

The network ID is the lowest address (boundary start) of the subnet containing the host.

Anahtar Kavram

Determining Network Address from IPv4 Host Address and CIDR Prefix

Soru 391Soru →

Match each IEEE 802.1Q trunking component or configuration behavior to its correct technical description.

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Cevap

Native VLAN frame egress behavior matches with un-tagged frame transmission. 802.1Q frame tagging mechanism matches with inserting a 4-byte field containing a 12-bit VLAN ID. Allowed VLAN list filtering matches with restricting allowed VLAN IDs across the trunk interface. Native VLAN mismatch condition matches with traffic leakage across differing native VLAN IDs and protocol warnings.

Each trunking feature maps to its core operational behavior under 802.1Q: native VLAN frames travel untagged; standard tagged frames carry a 4-byte 802.1Q header; allowed lists define authorized VLAN IDs; and native VLAN mismatches lead to cross-VLAN traffic leaking and administrative errors.

Adım Adım Çözüm

Analyze IEEE 802.1Q standard frame format requirements.

Identified that standard 802.1Q trunking inserts a 4-byte tag into frames for tagged VLANs, whereas native VLAN frames are transmitted untagged.

Understanding frame header modifications is essential for troubleshooting trunk link behavior.

Evaluate trunk interface filtering mechanisms.

Determined that allowed VLAN lists act as interface-level filters to prune unnecessary VLAN traffic from traversing trunk connections.

Restricting allowed VLANs conserves bandwidth and enhances network security across switch trunks.

Examine the operational impact of configuration discrepancies.

Confirmed that mismatched native VLAN configurations cause traffic sent untagged from one VLAN to be processed by the remote switch on a different VLAN.

Native VLAN consistency is critical to prevent unwanted broadcast domain merging and STP topology instability.

Anahtar Kavram

802.1Q Trunking Fundamentals and Native VLAN Processing

Soru 392Soru →

A network administrator executes a command-line query to verify how an application alias is configured in the domain zone file. The `dig` output displays the following answer section:

text
;; ANSWER SECTION:
app.example.com. 3600 IN CNAME web-server-01.example.com.

Which DNS record type is being used to map the alias hostname `app.example.com` to the canonical domain name `web-server-01.example.com`?

CNAME record

PTR record

AAAA record

MX record

Cevabı ve açıklamayı göster

Cevap: CNAME record

Cevap

The CNAME record is used to map an alias domain name to its canonical domain name.

The CNAME (Canonical Name) record is specifically designed to create an alias that points one domain name to another canonical domain name.

Adım Adım Çözüm

Examine the output snippet from the `dig` command.

The answer section shows `app.example.com. 3600 IN CNAME web-server-01.example.com.`.

The record type field in the resource record explicitly states `CNAME`.

Determine the functional role of the identified record type.

CNAME stands for Canonical Name, which creates an alias pointing to another hostname.

When a query is made for `app.example.com`, the DNS resolver follows the CNAME to `web-server-01.example.com` to obtain its IP address.

Anahtar Kavram

DNS Resource Record Types (CNAME)

Tahmini Süre:45s

Soru 393Soru →

A client computer on an enterprise network attempts to resolve the domain name www.example.com for the first time without any local cached records. Place the steps of the DNS lookup process in the correct chronological order from the initial request to receiving the IP address.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence starts with the client querying its local cache and local recursive DNS server, followed by the recursive server querying the Root Name Server, the TLD Name Server, and finally the Authoritative Name Server before returning the IP address to the client.

The standard DNS resolution flow moves from client stub resolver to local recursive resolver, then hierarchically traverses the DNS tree: Root Name Server -> TLD Name Server -> Authoritative Name Server, before caching and returning the IP address to the requesting host.

Adım Adım Çözüm

Initiate query locally

Client stub resolver checks cache and sends query to local recursive resolver.

Local resolution reduces unnecessary network traffic if the mapping is already known.

Query Root Server

Recursive resolver contacts a Root Name Server.

Root servers direct queries to the correct Top-Level Domain server (e.g., .com).

Query TLD Server

Recursive resolver contacts the TLD Server.

TLD servers maintain delegation records (NS records) pointing to the domain's authoritative name servers.

Query Authoritative Server

Recursive resolver requests the specific host record from the Authoritative Name Server.

Authoritative servers hold the actual mapping records (A/AAAA) for hostnames in their zone.

Return result to client

The IP address is cached by the recursive resolver and delivered to the client stub resolver.

Completes the DNS lookup lifecycle and enables network communication to the IP address.

Anahtar Kavram

DNS Recursive Resolution Hierarchy

Soru 394Soru →

A network administrator is configuring interface `GigabitEthernet1/0/12` on a switch to connect to a multi-tenant device. The device sends tagged frames for VLAN 200 (Data) and untagged frames for device management. The administrator needs to ensure that untagged management frames are assigned to VLAN 50 while allowing tagged VLAN 200 frames across the link. Which configuration snippet correctly satisfies these requirements?

switchport mode trunk
switchport trunk native vlan 50
switchport trunk allowed vlan 50,200

switchport mode trunk
switchport access vlan 50
switchport trunk allowed vlan 200

switchport mode access
switchport access vlan 50
switchport access vlan 200

switchport mode trunk
switchport trunk native vlan 200
switchport trunk allowed vlan 50

Cevabı ve açıklamayı göster

Cevap: switchport mode trunk
switchport trunk native vlan 50
switchport trunk allowed vlan 50,200

Cevap

The correct configuration enables 802.1Q trunking on the switchport, sets native VLAN 50 to process untagged management frames, and includes both VLAN 50 and VLAN 200 in the allowed VLAN list.

The correct choice configures the interface in trunking mode, sets the native VLAN to 50 (which maps all untagged incoming frames to VLAN 50), and permits both VLAN 50 and VLAN 200 across the trunk link.

Adım Adım Çözüm

Identify the trunking requirement

The link must carry both tagged traffic (VLAN 200) and untagged traffic (Management), requiring an 802.1Q trunk configuration.

Access mode interfaces support only one untagged VLAN, whereas trunks support multiple VLANs over a single physical port.

Map untagged traffic to the target management VLAN

Set the native VLAN on the trunk to 50 using `switchport trunk native vlan 50`.

By default, 802.1Q trunks assign untagged frames to VLAN 1; defining a custom native VLAN redirects untagged frames to VLAN 50.

Verify allowed VLAN list

Include VLAN 50 and VLAN 200 using `switchport trunk allowed vlan 50,200`.

Both the native VLAN and tagged VLANs must be permitted on the trunk interface to allow bidirectionally passed frames.

Anahtar Kavram

802.1Q Native VLAN & Trunk Allowed List Configuration

Soru 395Soru →

A network administrator is deploying OSPF across an enterprise edge router connected to a service provider. The administrator configures a static default route ( $0.0.0.0/0$ ) pointing toward the ISP gateway for external Internet destination handling. The internal routers within the enterprise network need to learn this default egress route automatically through the existing dynamic routing process without manually adding static routes to every downstream router. Which of the following configuration actions should the administrator perform on the edge router to fulfill this routing requirement?

Issue the default-information originate command within the OSPF routing process configuration.

Configure Port Address Translation (PAT) on the external interface connected to the ISP.

Change the default gateway interface encapsulation to assign incoming packets to Layer 2 frames.

Assign a High Availability Virtual IP (VIP) address to the edge router's WAN interface.

Cevabı ve açıklamayı göster

Cevap: Issue the default-information originate command within the OSPF routing process configuration.

Cevap

Issue the default-information originate command within the OSPF routing process configuration.

The correct action is to execute the default-information originate command under the OSPF router configuration mode. This command allows the autonomous system boundary router (ASBR) to inject the default route (

0.0.0.0/0

) into the OSPF domain, enabling all internal routers to dynamically learn the default path to external destinations.

Adım Adım Çözüm

Identify the goal of distributing an existing static default route (

0.0.0.0/0

) to internal dynamic routing peers.

Recognize that OSPF requires an explicit instruction to originate and advertise default routing information into the LSA database.

By default, OSPF does not automatically redistribute static routes, including default routes, without specific protocol configuration.

Evaluate the correct protocol command used to inject a default path into OSPF.

Determine that default-information originate advertises

0.0.0.0/0

into OSPF.

This command generates a Type 5 LSA to inform all interior OSPF routers of the default gateway path.

Anahtar Kavram

Default Route Redistribution and Origination in Dynamic Routing Protocols

Soru 396Soru →

A network administrator is reviewing how a link-state routing protocol like OSPF establishes network topology visibility and calculates paths. Place the operational steps of a link-state routing protocol in the correct chronological sequence, starting from initial neighbor discovery to final IP routing table entry installation.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct operational sequence begins with discovering neighbors via Hello packets, creating Link-State Advertisements (LSAs), flooding LSAs to build a synchronized Link-State Database (LSDB), executing the Dijkstra Shortest Path First (SPF) algorithm, and finally populating the IP routing table with the best paths.

Link-state dynamic routing protocols follow a strictly defined sequence of operations to achieve convergence. The process begins with neighbor discovery using Hello packets. Once adjacencies are established, routers generate Link-State Advertisements (LSAs) detailing their local interfaces and costs. These LSAs are flooded throughout the network area until every router holds an identical Link-State Database (LSDB). Each router then independently runs the Dijkstra Shortest Path First (SPF) algorithm on the LSDB to compute the shortest paths to all known destinations. Finally, the calculated best routes are populated into the router's IP routing table for forwarding operations.

Adım Adım Çözüm

Identify neighbor discovery phase

Routers send and receive Hello packets to find adjacent routers on active interfaces.

Direct communication must be established before control plane routing details can be exchanged.

Identify link state generation phase

Each router creates Link-State Advertisements (LSAs) representing its local link states and metrics.

Routers are only authoritative for the status of their directly connected networks.

Identify database synchronization phase

LSAs are flooded reliably across the routing area, building an identical Link-State Database (LSDB).

Link-state protocols require every router to possess the complete topology map of the area.

Identify path computation phase

Each router runs Dijkstra's Shortest Path First (SPF) algorithm locally using its LSDB.

The SPF algorithm processes the LSDB to construct a loop-free tree of shortest paths.

Identify route installation phase

The best paths from the SPF calculation are installed into the router's IP routing table.

The routing table holds the active forwarding entries used for handling incoming data packets.

Anahtar Kavram

Link-State Routing Protocol Convergence Sequence

Soru 397Soru →

A systems engineer queries an internal name server using the `nslookup` command to verify host address resolution for a database server:

text
> nslookup db01.contoso.local
Server: dns1.contoso.local
Address: 10.0.0.2

Name: db01.contoso.local
Address: 10.0.1.50

Which DNS resource record type provides this direct mapping of a hostname to an IPv4 address?

A record

AAAA record

PTR record

CNAME record

Cevabı ve açıklamayı göster

Cevap: A record

Cevap

An A record is used to resolve a hostname directly to an IPv4 address.

An A (Address) record is the fundamental DNS resource record type used to map a domain name or hostname to a standard 32-bit IPv4 address. In the command output, the hostname `db01.contoso.local` resolves directly to `10.0.1.50`, which represents a standard IPv4 forward lookup.

Adım Adım Çözüm

Analyze the output snippet from the `nslookup` command line tool.

The query for `db01.contoso.local` returned the IP address `10.0.1.50`.

Identifying the target data format (IPv4 address) is necessary to determine the corresponding DNS record type.

Evaluate the address format returned by the DNS query.

The address `10.0.1.50` is a 32-bit IPv4 address.

IPv4 host resolution requires a specific forward lookup resource record type.

Select the record type responsible for IPv4 host mapping.

The A (Address) record matches IPv4 forward mappings.

An A record specifically binds a domain name to an IPv4 address in DNS zone files.

Anahtar Kavram

DNS A Record IPv4 Resolution

Tahmini Süre:45s

Soru 398Soru →

An enterprise router receives routing updates for the identical destination network prefix (172.16.10.0/24) from two dynamic routing protocols: EIGRP and OSPF. Assuming default protocol settings and identical prefix lengths, which criterion determines which path the router places into its active IP routing table?

Administrative distance, selecting EIGRP because its default value of 90 is lower than OSPF's default value of 110

The raw protocol metric value, selecting OSPF because its cost metric uses smaller integer numbers than EIGRP composite metric values

Transport layer protocol classification, prioritizing OSPF because it uses Layer 4 connectionless delivery

Port Address Translation mapping priority, selecting the path with configured public IP translation rules

Cevabı ve açıklamayı göster

Cevap: Administrative distance, selecting EIGRP because its default value of 90 is lower than OSPF's default value of 110

Cevap

Administrative distance determines the path installed in the routing table, choosing EIGRP because its default administrative distance of 90 is lower than OSPF's 110.

When multiple routing protocols advertise the identical destination prefix, the router uses Administrative Distance (AD) to assess source trustworthiness. Internal EIGRP has a default AD of 90, whereas OSPF has a default AD of 110. Because 90 is lower than 110, the router selects the EIGRP path for installation into the routing table.

Adım Adım Çözüm

Check prefix length of competing routes

Both OSPF and EIGRP offer routes to the exact same prefix length (172.16.10.0/24).

Longest prefix match is evaluated first; since prefix lengths are equal (/24), the router proceeds to compare Administrative Distance.

Compare default Administrative Distance (AD) values

Internal EIGRP default AD = 90; OSPF default AD = 110.

Lower administrative distance represents a more trustworthy routing source.

Determine installed route

The router installs the EIGRP route into the active routing table.

EIGRP's administrative distance of 90 is lower than OSPF's administrative distance of 110.

Anahtar Kavram

Administrative Distance vs Metric in Route Selection

Soru 399Soru →

Match each 802.1Q switch interface configuration command with its corresponding operational behavior on an enterprise switch link.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

Matching pairs:
- 'switchport trunk native vlan 99' maps to 'Configures the interface to transmit and receive untagged traffic belonging to a designated non-default broadcast domain across the trunk.'
- 'switchport mode trunk' maps to 'Forces the interface into permanent trunking mode while continuing to send Dynamic Trunking Protocol (DTP) negotiation frames.'
- 'switchport trunk allowed vlan 10,20' maps to 'Prunes all traffic from the trunk link except for tagged frames matching the explicitly specified VLAN identification numbers.'
- 'switchport nonegotiate' maps to 'Prevents the interface from sending Dynamic Trunking Protocol (DTP) frames while operating in trunking mode.'

Each command directly aligns with standard 802.1Q trunk operational behaviors: native VLAN commands set the untagged broadcast domain, mode trunk forces 802.1Q encapsulation while keeping DTP active, allowed vlan restricts active VLAN IDs over the trunk, and nonegotiate suppresses DTP packets for enhanced security.

Adım Adım Çözüm

Analyze 'switchport trunk native vlan 99'

Identified as setting the 802.1Q native VLAN parameter to VLAN 99.

802.1Q trunking sends traffic for the native VLAN without inserting an 802.1Q header tag.

Analyze 'switchport mode trunk'

Identified as configuring unconditional trunking.

Statically setting trunk mode overrides dynamic auto/desirable modes, though DTP packets are still emitted unless explicitly suppressed.

Analyze 'switchport trunk allowed vlan 10,20'

Identified as configuring VLAN pruning on the trunk.

By default, all VLANs (1-4094) are allowed on a trunk link unless filtered using the allowed VLAN parameter.

Analyze 'switchport nonegotiate'

Identified as disabling Dynamic Trunking Protocol (DTP).

Security best practices recommend disabling unnecessary negotiation protocols on manually configured trunk links.

Anahtar Kavram

802.1Q Trunking Interface Commands and Operational Behaviors

Tahmini Süre:1m 30s

Soru 400Soru →

A network administrator is deploying a DHCP relay service on a Layer 3 boundary router to service workstations located on VLAN 40 ( $172.28.40.0/24$ ). The centralized corporate DHCP server is located on a distant management network at $10.50.1.100$ . Workstations on VLAN 40 are currently getting APIPA addresses ( $169.254.x.x$ ) because broadcast DHCPDISCOVER messages are stopped at the router. Which TWO of the following requirements or configuration steps are necessary on the router to allow clients on VLAN 40 to successfully obtain leases from the central DHCP server? (Select TWO.)

Geçerli olan tümünü seçin

Apply the IP helper address command targeting

10.50.1.100

specifically on the router interface or SVI directly attached to VLAN 40.

Ensure the router interface facing VLAN 40 has an active IPv4 address assigned in the

172.28.40.0/24

subnet to populate the Gateway IP Address (giaddr) field.

Configure the helper address command on the outbound WAN interface pointing toward the central DHCP server network.

Configure access control lists on the router to allow incoming TCP port 67 and TCP port 68 traffic from VLAN 40 workstations.

Cevabı ve açıklamayı göster

Cevap: Apply the IP helper address command targeting $10.50.1.100$ specifically on the router interface or SVI directly attached to VLAN 40.; Ensure the router interface facing VLAN 40 has an active IPv4 address assigned in the $172.28.40.0/24$ subnet to populate the Gateway IP Address (giaddr) field.

Cevap

The administrator must apply the IP helper address command targeting

10.50.1.100

directly on the VLAN 40 interface/SVI, and ensure that the interface facing VLAN 40 has an active IPv4 address in the

172.28.40.0/24

subnet to populate the giaddr header field.

To successfully relay DHCP traffic across Layer 3 boundaries, the router must intercept client broadcast traffic on the local client-facing interface (VLAN 40) where the `ip helper-address` command is applied. Additionally, the router uses the IP address configured on that client-facing interface to fill the `giaddr` (Gateway IP Address) field in the DHCP packet header. This field informs the remote DHCP server which subnet scope to select for assigning an IP address lease.

Adım Adım Çözüm

Identify the ingress boundary interface for client DHCP broadcasts.

The router interface/SVI connected directly to VLAN 40 is identified as the ingress point for broadcast DHCPDISCOVER frames.

Routers drop Layer 2 broadcasts by default. The relay agent must listen on the incoming interface receiving the broadcasts.

Configure the DHCP relay statement on the client-facing interface.

Applying `ip helper-address 10.50.1.100` on the VLAN 40 interface enables the conversion of incoming broadcasts to unicast packets sent to the server.

This tells the router where to forward unicast DHCP requests across routing boundaries.

Verify giaddr field population requirements.

The router inserts its own IP address from the VLAN 40 interface into the `giaddr` field of the unicast DHCP packet.

The centralized DHCP server reads the `giaddr` value to determine which IP address pool (

172.28.40.0/24

) to issue a lease from.

Anahtar Kavram

DHCP Relay Agent Operation and Gateway IP Address (giaddr) Insertion

ÖncekiSayfa 20 / 22Sonraki

Network Implementation

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