Tüm alıştırma soruları

1987 soru

Tüm türler1,987 Çoktan seçmeli1,020 Çoklu seçim452 Sayısal18 Eşleştirme229 Sıralama203 Boşluk doldurma22 Kısa cevap43

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

text
Gateway of last resort is 192.168.1.1 to network 0.0.0.0

S* 0.0.0.0/0 [1/0] via 192.168.1.1
10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
O 10.150.0.0/16 [110/20] via 172.16.1.1, 00:10:22, GigabitEthernet0/0/1
D 10.150.45.128/25 [90/307200] via 172.16.2.1, 00:05:12, GigabitEthernet0/0/2
S 10.150.45.136/29 [1/0] via 172.16.3.1
O 10.150.45.136/30 [110/50] via 172.16.4.1, 00:01:45, GigabitEthernet0/0/3

The router receives an IPv4 packet destined for $10.150.45.138$ . Which next-hop IP address will the router select to forward this packet?

172.16.4.1

172.16.3.1

172.16.2.1

172.16.1.1

Cevabı ve açıklamayı göster

Cevap: 172.16.4.1

Cevap

The router forwards the packet to next-hop IP address 172.16.4.1.

When a router receives a packet, it compares the destination IP address against all entries in its routing table. The rule of Longest Prefix Match (LPM) dictates that the route with the most specific (longest) subnet mask is selected. The target IP address 10.150.45.138 matches multiple routes, but 10.150.45.136/30 has the longest prefix mask (/30 vs /29, /25, /16, /0). The next-hop IP for 10.150.45.136/30 is 172.16.4.1.

Adım Adım Çözüm

Identify all candidate routes matching the destination IP address 10.150.45.138.

Matching routes in table: 0.0.0.0/0, 10.150.0.0/16, 10.150.45.128/25, 10.150.45.136/29, and 10.150.45.136/30.

The IP address 10.150.45.138 falls within the address range of all listed subnets.

Compare the prefix lengths (subnet masks) of all matching routes to determine the Longest Prefix Match (LPM).

Prefix lengths are /0, /16, /25, /29, and /30. The /30 prefix is the longest and most specific match.

Cisco IP forwarding logic evaluates subnet mask length first before checking Administrative Distance or metric.

Determine the next-hop IP address associated with the winning /30 route.

Route 10.150.45.136/30 points to next-hop IP 172.16.4.1.

The router selects the next-hop tied directly to the route entry with the longest prefix match.

Anahtar Kavram

Router Forwarding Decision Logic (Longest Prefix Match Rule)

Tahmini Süre:1m 30s

Soru 1342Soru →

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

text
Gateway of last resort is 10.10.10.1 to network 0.0.0.0

D 192.168.16.0/20 [90/307200] via 10.1.1.2, GigabitEthernet0/0
O 192.168.24.0/22 [110/20] via 10.2.2.2, GigabitEthernet0/1
S 192.168.24.0/24 [1/0] via 10.3.3.2, GigabitEthernet0/2
S* 0.0.0.0/0 [1/0] via 10.10.10.1, GigabitEthernet0/3

Which TWO statements correctly describe how the router makes forwarding decisions based on this routing table?

Geçerli olan tümünü seçin

A packet with destination IP 192.168.24.45 is routed via GigabitEthernet0/2 because 192.168.24.0/24 represents the longest prefix match.

Longest prefix match is evaluated first during packet forwarding lookup, independent of administrative distance values across different prefix lengths.

A packet with destination IP 192.168.24.45 is routed via GigabitEthernet0/0 because EIGRP has a lower administrative distance than OSPF.

Traffic for destination IP 192.168.24.45 is load-balanced across GigabitEthernet0/1 and GigabitEthernet0/2 because their subnet boundaries overlap.

Cevabı ve açıklamayı göster

Cevap: A packet with destination IP 192.168.24.45 is routed via GigabitEthernet0/2 because 192.168.24.0/24 represents the longest prefix match.; Longest prefix match is evaluated first during packet forwarding lookup, independent of administrative distance values across different prefix lengths.

Cevap

The router routes traffic destined for 192.168.24.45 out interface GigabitEthernet0/2 using the longest prefix match (/24), and longest prefix match logic is evaluated prior to administrative distance during the forwarding lookup.

When a router receives a packet, it compares the packet's destination IP address against all network entries in its routing table. The rule of Longest Prefix Match (LPM) specifies that the route with the most specific (longest) subnet mask is chosen for forwarding, regardless of protocol or administrative distance. Furthermore, administrative distance is utilized when populating the routing table between equal prefix matches, not during the packet packet forwarding lookup process.

Adım Adım Çözüm

Evaluate all candidate matching routes for destination address 192.168.24.45.

The destination falls within 192.168.16.0/20 (range 192.168.16.0–192.168.31.255), 192.168.24.0/22 (range 192.168.24.0–192.168.27.255), 192.168.24.0/24 (range 192.168.24.0–192.168.24.255), and 0.0.0.0/0.

Routing decision logic compares the destination binary pattern against all active routes in the RIB.

Determine the winning route based on the Longest Prefix Match (LPM) rule.

192.168.24.0/24 has 24 matching bits, which is the maximum matching prefix length among all candidate entries.

The router always selects the route entry with the highest number of matching leading bits.

Analyze the relationship between Administrative Distance (AD) and Longest Prefix Match.

Administrative distance is used during routing table selection when installing paths from different routing sources with exact matching prefixes. For packet forwarding lookups, LPM is evaluated first.

Administrative distance does not override a longer subnet mask during packet forwarding decisions.

Anahtar Kavram

Router Forwarding Decision Logic (Longest Prefix Match precedence over Administrative Distance)

Soru 1343Soru →

An enterprise Cisco IOS-XE router displays the following IPv4 routing table entries:

text
Gateway of last resort is not set

172.16.0.0/16 is variably subnetted, 4 subnets, 3 masks
O 172.16.10.0/24 [110/65] via 10.0.0.1, 01:15:22, GigabitEthernet0/1
D 172.16.10.0/25 [90/307200] via 10.0.0.2, 00:45:10, GigabitEthernet0/2
S 172.16.0.0/16 [1/0] via 10.0.0.3
C 172.16.10.128/25 is directly connected, GigabitEthernet0/3

Which two statements correctly describe how the router processes traffic based on these routing table components?

Geçerli olan tümünü seçin

A packet destined to 172.16.10.50 is forwarded out interface GigabitEthernet0/2 because the /25 EIGRP route represents the longest prefix match.

A packet destined to 172.16.10.200 is forwarded out interface GigabitEthernet0/3 because the connected subnet 172.16.10.128/25 is the longest prefix match.

A packet destined to 172.16.10.50 is forwarded via next-hop 10.0.0.3 because the static route has the lowest Administrative Distance.

A packet destined to 172.16.10.200 is forwarded via next-hop 10.0.0.1 because the OSPF route has a lower metric than the connected interface.

Cevabı ve açıklamayı göster

Cevap: A packet destined to 172.16.10.50 is forwarded out interface GigabitEthernet0/2 because the /25 EIGRP route represents the longest prefix match.; A packet destined to 172.16.10.200 is forwarded out interface GigabitEthernet0/3 because the connected subnet 172.16.10.128/25 is the longest prefix match.

Cevap

Packets destined to 172.16.10.50 are egressed via GigabitEthernet0/2 due to the /25 EIGRP route being the longest prefix match, and packets destined to 172.16.10.200 are egressed via GigabitEthernet0/3 because the connected /25 route provides the longest prefix match for that address range.

Router forwarding decision logic evaluates routes using the Longest Prefix Match (LPM) rule. For 172.16.10.50, the EIGRP subnet 172.16.10.0/25 (/25 mask length) is longer than the OSPF /24 and static /16 routes. For 172.16.10.200, the directly connected subnet 172.16.10.128/25 (/25 mask length) is longer than the OSPF /24 and static /16 routes. Thus, both statements reflecting LPM selections out GigabitEthernet0/2 and GigabitEthernet0/3 are correct.

Adım Adım Çözüm

Analyze matching prefix routes for destination address 172.16.10.50.

Destination 172.16.10.50 matches 172.16.0.0/16 (static), 172.16.10.0/24 (OSPF), and 172.16.10.0/25 (EIGRP range 172.16.10.0 - 172.16.10.127).

Routing decisions prioritize prefix mask length over Administrative Distance or metric.

Determine the forwarding interface for 172.16.10.50.

The /25 route (172.16.10.0/25) has the longest mask length. Traffic is routed via 10.0.0.2 out GigabitEthernet0/2.

Longest Prefix Match (LPM) rule dictates selecting the longest subnet mask among all matching routes.

Analyze matching prefix routes for destination address 172.16.10.200.

Destination 172.16.10.200 matches 172.16.0.0/16 (static), 172.16.10.0/24 (OSPF), and 172.16.10.128/25 (Connected range 172.16.10.128 - 172.16.10.255). It does NOT match 172.16.10.0/25.

Address 172.16.10.200 falls strictly into the upper half of the /24 network block.

Determine the forwarding interface for 172.16.10.200.

The connected route 172.16.10.128/25 has the longest prefix match (/25 vs /24 vs /16). Traffic egresses directly out GigabitEthernet0/3.

LPM resolution selects /25 over /24 and /16.

Anahtar Kavram

Longest Prefix Match (LPM) Rule in Cisco IPv4 Forwarding

Soru 1344Soru →

A network technician needs to connect a workstation's Ethernet network interface card directly to a Cisco router's GigabitEthernet interface for initial device staging without using an intermediate switch. Auto-MDIX has been manually disabled on the router interface. Which cable type is required to successfully establish Layer 1 link integrity between these two devices?

A crossover cable with all four wire pairs transposed between opposing connectors

A standard straight-through cable, because workstations and router interfaces naturally use opposing MDI and MDI-X pinouts

A rollover cable terminated with RJ-45 connectors on both ends

A crossover cable with only pin pairs 1/2 and 3/6 transposed

Cevabı ve açıklamayı göster

Cevap: A crossover cable with all four wire pairs transposed between opposing connectors

Cevap

A crossover cable with all four wire pairs transposed between opposing connectors

The correct option is the choice describing a crossover cable with all four wire pairs transposed. Ethernet interfaces on end-user PCs and routers both use standard MDI pinouts. When connecting two MDI devices directly without an intervening switch (MDI-X) and with Auto-MDIX disabled, the physical transmit conductors of one device must connect to the receive conductors of the other. Furthermore, 1000BASE-T GigabitEthernet utilizes all four wire pairs for data, requiring all four pairs to be crossed over.

Adım Adım Çözüm

Identify the pinout role (MDI vs MDI-X) of each connected device

Both the host workstation NIC and the Cisco router interface are classified as MDI (Media Dependent Interface) devices.

MDI devices transmit data on specific pins and receive on others. Like devices (MDI-to-MDI or MDIX-to-MDIX) transmit on the same pins.

Determine the required cable configuration based on Auto-MDIX state

Because Auto-MDIX is disabled, a crossover cable must be used to swap the transmit and receive line pairs.

Without Auto-MDIX automatically remapping signals in hardware, a straight-through cable results in transmit signals connecting directly to transmit signals on the opposite end.

Account for the interface speed specification (GigabitEthernet / 1000BASE-T)

All four wire pairs (1/2, 3/6, 4/5, 7/8) must be transposed.

Unlike 10/100 Mbps Ethernet which uses two pairs, 1000BASE-T operates over all four copper pairs simultaneously.

Anahtar Kavram

MDI/MDI-X pinouts and 1000BASE-T crossover requirements

Tahmini Süre:1m 0s

Soru 1345Soru →

A network administrator is setting up a wireless network for guest access on a Cisco Wireless LAN Controller (WLC). The Profile Name and SSID have already been defined. To ensure that all client traffic associated with this WLAN is assigned to VLAN 30, which action must the administrator take within the WLAN edit settings in the WLC GUI?

Select the interface mapped to VLAN 30 from the Interface/Interface Group drop-down list on the General tab.

Specify VLAN 30 in the Helper IP Address field on the Advanced tab.

Enable 802.1Q Trunk Tagging under the Security Layer 2 configuration tab.

Change the AP Mode to FlexConnect and configure VLAN 30 on the Wireless General tab.

Cevabı ve açıklamayı göster

Cevap: Select the interface mapped to VLAN 30 from the Interface/Interface Group drop-down list on the General tab.

Cevap

Select the interface mapped to VLAN 30 from the Interface/Interface Group drop-down list on the General tab.

When configuring client network access on a Cisco WLC via the GUI, binding a WLAN to a dynamic interface (which corresponds to a specific VLAN such as VLAN 30) is performed under the General tab using the Interface/Interface Group drop-down menu.

Adım Adım Çözüm

Navigate to the WLANs menu in the WLC GUI and open the target WLAN edit page.

The WLANs > Edit screen opens showing configuration tabs.

WLAN-specific parameters are managed within the WLAN edit view.

Locate the General tab settings.

Access profile parameters including Profile Name, SSID, Status, and Interface/Interface Group.

The General tab contains core WLAN settings including state and interface binding.

Select the desired dynamic interface bound to VLAN 30 from the Interface/Interface Group drop-down list.

The WLAN is associated with the selected dynamic interface.

Binding the interface maps wireless client traffic to the appropriate Layer 2 VLAN/subnet.

Anahtar Kavram

WLAN Interface Mapping in Cisco WLC GUI

Soru 1346Soru →

An administrator enables IPv6 autoconfiguration on a network host interface with a burned-in hardware MAC address of 70-69-5A-12-34-B5. Which two statements regarding the generated EUI-64 interface identifier and link-local address are correct?

Geçerli olan tümünü seçin

The generated interface identifier is 7269:5aff:fe12:34b5.

The automatically assigned link-local address uses the prefix fe80::/10.

The 16-bit hexadecimal string ffff is inserted between the OUI and the device identifier.

The 7th bit of the first byte remains unchanged as 0 to indicate a universally administered address.

Cevabı ve açıklamayı göster

Cevap: The generated interface identifier is 7269:5aff:fe12:34b5.; The automatically assigned link-local address uses the prefix fe80::/10.

Cevap

The correct statements are that the generated interface identifier is 7269:5aff:fe12:34b5 and the link-local address uses the prefix fe80::/10.

Generating an IPv6 EUI-64 interface identifier from a 48-bit MAC address requires splitting the MAC address into two 24-bit halves, inserting fffe into the middle, and inverting the 7th bit (Universal/Local bit) of the first byte. For the MAC 70-69-5A-12-34-B5, the byte 70 (0111 0000) becomes 72 (0111 0010), producing the interface ID 7269:5aff:fe12:34b5. Furthermore, all IPv6 link-local autoconfigured addresses use the standardized prefix fe80::/10.

Adım Adım Çözüm

Split the 48-bit MAC address into two 24-bit halves

Left half: 70-69-5A, Right half: 12-34-B5

EUI-64 creation requires inserting a fixed 16-bit value between the Organizationally Unique Identifier (OUI) and the NIC-specific identifier.

Insert the hexadecimal string fffe between the two halves

7069:5AFF:FE12:34B5

The IEEE EUI-64 standard specifies the insertion of FFFE into the midpoint of a 48-bit MAC address.

Invert the 7th bit (Universal/Local bit) of the first byte

Hex 70 (binary 0111 0000) becomes Hex 72 (binary 0111 0010), yielding the interface ID 7269:5aff:fe12:34b5

In EUI-64 formatting, the 7th bit of the first octet is inverted to indicate local scope/modification.

Combine the interface identifier with the IPv6 link-local prefix

fe80::7269:5aff:fe12:34b5 (prefix range fe80::/10)

Link-local addresses in IPv6 use the reserved prefix range fe80::/10.

Anahtar Kavram

IPv6 EUI-64 Interface Identifier Derivation and Link-Local Addressing

Tahmini Süre:1m 30s

Soru 1347Soru →

A network administrator is creating a wireless LAN for corporate clients using the Cisco Wireless LAN Controller (WLC) GUI. Which TWO actions must be completed within the WLAN edit parameters to ensure client traffic is bound to the appropriate network segment and the WLAN becomes operational for client association? (Select TWO.)

Geçerli olan tümünü seçin

Map the WLAN to the designated client dynamic interface or interface group on the General tab.

Check the Status box on the General tab to enable the WLAN.

Configure TACACS+ server credentials under the AAA Servers tab to authenticate 802.1X wireless client associations.

Enable Local Mode operation on the Advanced tab so client traffic continues switching locally if WLC connectivity is lost.

Cevabı ve açıklamayı göster

Cevap: Map the WLAN to the designated client dynamic interface or interface group on the General tab.; Check the Status box on the General tab to enable the WLAN.

Cevap

Mapping the WLAN to the designated dynamic interface on the General tab and checking the Status checkbox to enable the WLAN are both required steps.

When configuring a WLAN in the Cisco WLC GUI, client connectivity requires assigning the WLAN to a dynamic interface (or interface group) under the General tab so that traffic is mapped to the correct VLAN. Additionally, because new WLAN profiles are disabled by default, selecting the Status checkbox on the General tab is mandatory to broadcast the SSID and accept client associations.

Adım Adım Çözüm

Identify interface mapping requirements in WLC GUI

Dynamic interface is configured under WLANs > Edit > General tab > Interface/Interface Group dropdown.

This binds the wireless network (SSID) to a specific Layer 2 VLAN/subnet on the wired infrastructure.

Identify WLAN operational status requirement

Check the Enabled box next to Status on the General tab.

Cisco WLC WLAN profiles are created in a disabled state by default and will not broadcast or accept associations until explicitly enabled.

Anahtar Kavram

WLC GUI WLAN Basic Parameters and Enablement

Soru 1348Soru →

A network engineer must configure path redundancy on a Cisco IOS router for reaching the remote IPv6 prefix $2001:\text{db8}:4000:50::/64$ . The primary path must forward packets through interface GigabitEthernet0/0/1 using the next-hop router's link-local IPv6 address $\text{fe80}::2$ . The secondary backup path must forward packets toward the global unicast next-hop IPv6 address $2001:\text{db8}:1000:20::2$ only if the primary path fails. Which TWO Cisco IOS commands are required to satisfy these requirements?

Geçerli olan tümünü seçin

ipv6 route 2001:db8:4000:50::/64 GigabitEthernet0/0/1 fe80::2

ipv6 route 2001:db8:4000:50::/64 2001:db8:1000:20::2 130

ipv6 route 2001:db8:4000:50::/64 fe80::2

ipv6 route 2001:db8:4000:50::/64 GigabitEthernet0/0/2 2001:db8:1000:20::2

Cevabı ve açıklamayı göster

Cevap: ipv6 route 2001:db8:4000:50::/64 GigabitEthernet0/0/1 fe80::2; ipv6 route 2001:db8:4000:50::/64 2001:db8:1000:20::2 130

Cevap

The correct configuration requires both the command specifying the local exit interface alongside the link-local next-hop address ('ipv6 route 2001:db8:4000:50::/64 GigabitEthernet0/0/1 fe80::2') and the command defining a higher administrative distance for the backup route ('ipv6 route 2001:db8:4000:50::/64 2001:db8:1000:20::2 130').

The combination of using a fully-specified route syntax for link-local next-hops ('GigabitEthernet0/0/1 fe80::2') and appending an elevated Administrative Distance of 130 for the global unicast backup path ensures that link-local scoping syntax rules are respected and that the backup route remains floating until primary path failure.

Adım Adım Çözüm

Analyze link-local IPv6 static routing requirements.

Link-local addresses (fe80::/10) are only unique per link. Cisco IOS cannot determine which interface to send traffic through if only a link-local next-hop address is provided. Therefore, the exit interface MUST be specified when using a link-local next-hop.

Ensures proper outgoing interface binding for link-scoped IPv6 destinations.

Analyze floating static route AD requirements.

To configure a floating static route as a secondary backup path, an Administrative Distance (AD) higher than default static routes (AD 1) must be explicitly appended to the command (e.g., AD 130).

Prevents the secondary route from populating the IPv6 routing table while the primary route is active.

Anahtar Kavram

IPv6 Static Route Syntax & Floating Static Administrative Distance

Soru 1349Soru →

A Cisco IOS router (R1) is configured with three routes for the destination prefix $192.168.10.0/24$ : a primary static route (`ip route 192.168.10.0 255.255.255.0 10.0.12.2`), an active OSPFv2 dynamic route (Administrative Distance 110 via $10.0.14.2$ ), and a backup floating static route (`ip route 192.168.10.0 255.255.255.0 10.0.13.2 120`). Place the control plane and data plane events in the correct chronological sequence starting immediately after the physical interface connected to $10.0.12.2$ fails.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence of events is: Interface link failure → Primary static route RIB withdrawal → AD evaluation selecting OSPF over floating static → FIB table update → Forwarding of packets via the OSPF path.

When an active egress interface fails, Cisco IOS immediately removes the connected static route from the Routing Information Base (RIB). The router then re-evaluates all available candidate routes for the exact destination prefix (

192.168.10.0/24

). Because the prefix lengths are identical, the router compares Administrative Distance (AD). OSPF (AD 110) is preferred over the floating static route (AD 120). Once the RIB settles on the OSPF path, the control plane programs the Forwarding Information Base (FIB), and data plane traffic resumes forwarding out the OSPF next-hop.

Adım Adım Çözüm

Identify link status change

Interface going down invalidates directly associated static route next-hops.

Cisco IOS requires an active interface to keep static routes active in the RIB.

Withdraw primary static route from RIB

Primary static route with Administrative Distance 1 is purged.

Unreachable next-hop interfaces trigger route removal.

Compare Administrative Distance of remaining matching prefixes

OSPF route (AD 110) is selected instead of the floating static route (AD 120).

When prefix lengths match exactly (

192.168.10.0/24

), the route with the lowest Administrative Distance is installed.

Update Cisco Express Forwarding (CEF) FIB hardware tables

FIB updates pointer for

192.168.10.0/24

to point to

10.0.14.2

RIB modifications must sync to the FIB for hardware-accelerated forwarding.

Process data plane traffic

Packets targeting

192.168.10.50

switch path to

10.0.14.2

Subsequent ingress traffic matches the newly installed FIB lookup entry.

Anahtar Kavram

IPv4 Static Route RIB Lifecycle, Floating Static Administrative Distance Calibration, and CEF FIB Convergence

Soru 1350Soru →

A network switch interface has a burned-in MAC address of `3464.a912.3456`. When calculating an IPv6 address using the standard IEEE EUI-64 process, what is the generated 64-bit interface identifier expressed in standard colon-separated IPv6 hexadecimal notation?

Cevabı ve açıklamayı göster

Cevap: 3664:a9ff:fe12:3456; 3664:A9FF:FE12:3456

Cevap

3664:a9ff:fe12:3456

Converting the MAC address 34-64-A9-12-34-56 to EUI-64 format requires inserting FFFE into the middle (34-64-A9-FF-FE-12-34-56) and inverting the 7th bit of the first byte (0x34 becomes 0x36). Grouping into 16-bit hexadecimal blocks separated by colons yields 3664:a9ff:fe12:3456.

Adım Adım Çözüm

Split the 48-bit MAC address into two 24-bit halves.

Left half: 34:64:A9, Right half: 12:34:56.

EUI-64 requires inserting a specific 16-bit hexadecimal value into the midpoint of the MAC address.

Insert the hexadecimal value FFFE between the two halves.

34-64-A9-FF-FE-12-34-56

IEEE EUI-64 standard specifies the insertion of FFFE to expand a 48-bit MAC address to 64 bits.

Invert the 7th bit (Universal/Local bit) of the first byte (0x34).

Binary 0x34 = 0011 0100; inverted 7th bit = 0011 0110 = 0x36. The updated byte sequence is 36-64-A9-FF-FE-12-34-56.

The Universal/Local (U/L) bit is flipped to indicate a globally unique, modified EUI-64 address.

Format the resulting 64-bit value into IPv6 colon-separated hexadecimal quads.

3664:a9ff:fe12:3456

IPv6 interface identifiers are written as four 16-bit hexadecimal blocks separated by colons.

Anahtar Kavram

EUI-64 Interface Identifier Derivation

Soru 1351Soru →

An enterprise network administrator is evaluating Layer 2 protocol operations after migrating the switch infrastructure to Rapid PVST+. Which two statements correctly describe Rapid PVST+ port roles and operational state behaviors?

Geçerli olan tümünü seçin

Rapid PVST+ consolidates the legacy 802.1D Disabled, Blocking, and Listening port states into a single Discarding state.

An Alternate port receives BPDUs from neighboring switches and acts as a backup path to the Root Bridge.

Enabling PortFast on switch-to-switch trunk links accelerates convergence without risking transient Layer 2 loops.

The bridge priority value for a VLAN can be configured to any arbitrary integer between 0 and 65535, such as 8000.

Cevabı ve açıklamayı göster

Cevap: Rapid PVST+ consolidates the legacy 802.1D Disabled, Blocking, and Listening port states into a single Discarding state.; An Alternate port receives BPDUs from neighboring switches and acts as a backup path to the Root Bridge.

Cevap

Rapid PVST+ consolidates the legacy Disabled, Blocking, and Listening states into a single Discarding state, and an Alternate port acts as a backup path to the Root Bridge by receiving BPDUs from other switches.

Rapid PVST+ simplifies the standard 802.1D spanning tree model by merging the Disabled, Blocking, and Listening states into a single Discarding state. Furthermore, an Alternate port receives superior BPDUs from neighbor switches, allowing it to immediately assume the Root Port role if the active Root Port loses connectivity.

Adım Adım Çözüm

Analyze port state changes from standard 802.1D to Rapid PVST+ (802.1w).

Identify that Rapid PVST+ simplifies port states down to Discarding, Learning, and Forwarding.

Combining Disabled, Blocking, and Listening into Discarding streamlines state evaluation.

Evaluate the definition and function of the Alternate port role in Rapid PVST+.

Confirm that an Alternate port offers an alternate path toward the Root Bridge when it receives BPDUs from neighboring switches.

Alternate ports provide rapid uplink failover without requiring a full re-convergence cycle.

Identify misconceptions regarding PortFast misconfiguration and Bridge Priority increments.

Reject the options asserting arbitrary priority integers (like 8000) and PortFast deployment on inter-switch trunks.

Bridge priorities require increments of 4096 due to the System ID Extension, and PortFast on trunks risks broadcast storms.

Anahtar Kavram

Rapid PVST+ Operational States, Port Roles, and Priority Increments

Soru 1352Soru →

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

text
Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 4 subnets, 4 masks
O 10.88.164.32/28 [110/50] via 192.168.12.2, 00:14:22, GigabitEthernet0/0/1
D 10.88.164.0/25 [90/307200] via 192.168.23.3, 01:45:10, GigabitEthernet0/0/2
S 10.88.160.0/20 [1/0] via 192.168.34.4, 12:00:05, GigabitEthernet0/0/3
R 10.88.164.32/29 [120/2] via 192.168.45.5, 00:00:18, GigabitEthernet0/0/4

A packet with destination IP address $10.88.164.37$ arrives at the router. Which two statements correctly describe how the router processes and forwards this packet?

Geçerli olan tümünü seçin

The router forwards the packet via next-hop 192.168.45.5 out interface GigabitEthernet0/0/4.

Longest prefix match is evaluated prior to administrative distance and routing protocol metric.

The router forwards the packet via next-hop 192.168.34.4 because static routes take precedence due to an administrative distance of 1.

The router forwards the packet via next-hop 192.168.23.3 because EIGRP routes are preferred over RIP and OSPF routes.

Cevabı ve açıklamayı göster

Cevap: The router forwards the packet via next-hop 192.168.45.5 out interface GigabitEthernet0/0/4.; Longest prefix match is evaluated prior to administrative distance and routing protocol metric.

Cevap

The router forwards the packet via next-hop 192.168.45.5 out GigabitEthernet0/0/4, because longest prefix match is evaluated before administrative distance and metric.

When a router receives an IP packet, it searches its routing table for routes that enclose the destination IP address. If multiple routes match, the router strictly selects the route with the longest prefix mask (most specific network mask). Here, 10.88.164.32/29 matches 10.88.164.37 with 29 bits of match, which is longer than /28, /25, or /20. Therefore, the router forwards the packet to 192.168.45.5 via GigabitEthernet0/0/4. Administrative distance and metrics are never considered across different prefix lengths.

Adım Adım Çözüm

Determine subnet ranges for all matching candidate routes in the routing table for destination IP 10.88.164.37.

Candidate 1: 10.88.164.32/28 (10.88.164.32–10.88.164.47, prefix /28). Candidate 2: 10.88.164.0/25 (10.88.164.0–10.88.164.127, prefix /25). Candidate 3: 10.88.160.0/20 (10.88.160.0–10.88.175.255, prefix /20). Candidate 4: 10.88.164.32/29 (10.88.164.32–10.88.164.39, prefix /29). All 4 routes match destination 10.88.164.37.

A route is a candidate match if the target IP falls anywhere within its subnet block.

Apply the Longest Prefix Match (LPM) rule by comparing the subnet mask prefix lengths.

The prefix lengths are /20, /25, /28, and /29. The /29 route (10.88.164.32/29) has the highest number of matching network bits.

In Cisco IOS forwarding logic, the router always selects the route with the longest prefix match regardless of administrative distance or metric.

Identify the egress path associated with the winning route.

The 10.88.164.32/29 route points to next-hop IP 192.168.45.5 out interface GigabitEthernet0/0/4.

The packet is forwarded according to the forwarding table details bound to the longest matching route.

Anahtar Kavram

Router Forwarding Decision Logic & Longest Prefix Match (LPM)

Tahmini Süre:2m 0s

Soru 1353Soru →

Two Cisco routers are directly connected via their GigabitEthernet 0/0 interfaces in OSPFv2 Area 0. Router R1 maintains the default interface timers. An administrator executes the command `ip ospf hello-interval 15` on interface GigabitEthernet 0/0 of Router R2, but makes no other configuration changes on either router. What is the impact of this configuration on the OSPF neighbor relationship?

The routers fail to form an OSPF neighbor relationship because OSPF Hello and Dead intervals must match between directly connected neighbors.

The routers successfully form a FULL neighbor relationship because Dead intervals automatically recalculate to four times the configured Hello interval.

The routers establish an adjacency but remain permanently stuck in the 2-WAY state.

The routers establish an adjacency, but routing update exchanges occur every 15 seconds instead of every 10 seconds.

Cevabı ve açıklamayı göster

Cevap: The routers fail to form an OSPF neighbor relationship because OSPF Hello and Dead intervals must match between directly connected neighbors.

Cevap

The routers fail to form an OSPF neighbor relationship because OSPF Hello and Dead intervals must match between directly connected neighbors.

For two routers to form an OSPFv2 neighbor relationship on a link, specific parameters in their Hello packets must match. These include the Area ID, Subnet Mask, Hello Interval, Dead Interval, Authentication settings, and Stub flag. Modifying the Hello interval on Router R2 to 15 seconds causes a mismatch with Router R1's default 10-second Hello interval, leading both routers to reject incoming Hello packets.

Adım Adım Çözüm

Identify the mandatory parameters required for OSPFv2 neighbor adjacency.

OSPF Hello packets contain field values that must match between neighbors: Area ID, Subnet Mask, Hello Interval, Dead Interval, Authentication Password/Digest, and Stub Area Flag.

If any mandatory parameter mismatches, the received Hello packet is dropped and neighbor discovery fails.

Analyze the effect of modifying the Hello interval on Router R2.

Router R2 sends Hello packets containing a Hello interval of 15 seconds and a Dead interval of 60 seconds (default

4 \times \text{Hello}

). Router R1 sends Hello packets with a Hello interval of 10 seconds and a Dead interval of 40 seconds.

Changing the Hello interval on one router creates a mismatch with the default Hello interval on the neighboring router.

Determine the resulting neighbor state.

Because the Hello and Dead intervals in the incoming Hello packets do not match the local interface settings, both routers drop each other's Hello packets, preventing an adjacency from forming.

Directly connected OSPF neighbors must have identical Hello and Dead timer values on the connecting interface segment.

Anahtar Kavram

OSPFv2 Hello and Dead Timer Matching Requirements

Tahmini Süre:1m 0s

Soru 1354Soru →

Two Cisco routers, R1 and R2, are directly connected via their GigabitEthernet0/0 interfaces in OSPFv2 Area 0. Interface GigabitEthernet0/0 on R1 is configured with a maximum transmission unit (MTU) of 1500 bytes, whereas GigabitEthernet0/0 on R2 is configured with an MTU of 1400 bytes. Neither router has the ip ospf mtu-ignore command configured.

In which specific OSPF neighbor state will the adjacency between R1 and R2 become stuck?

Cevabı ve açıklamayı göster

Cevap: ExStart; EXSTART; ExStart state; EXSTART state

Cevap

ExStart

When OSPF neighbor parameters in Hello packets match, routers establish two-way communication and progress to the ExStart state to begin Database Description (DBD) packet negotiation. Because interface MTU values are advertised inside DBD headers, an MTU mismatch (1500 bytes on R1 vs. 1400 bytes on R2) causes the router with the lower MTU to ignore incoming DBD packets. As a result, Master/Slave election and DBD sequence number synchronization fail, leaving the neighbor relationship stuck in the ExStart state.

Adım Adım Çözüm

Analyze OSPF Hello packet processing and initial state transitions

Hello parameters (Area ID, Subnet Mask, Hello/Dead timers, Authentication) match between R1 and R2, allowing the routers to pass the Init state and transition into the 2-Way state.

MTU values are not contained or evaluated within OSPF Hello packets.

Evaluate Database Description (DBD) packet negotiation during ExStart

Upon transitioning to the ExStart state, routers exchange Database Description (DBD) packets to elect a Master/Slave relationship and negotiate sequence numbers. The configured interface MTU is explicitly included in the Interface MTU field of the DBD header.

OSPF requires matching interface MTUs to ensure Database Description packets carrying Link-State Advertisements can be exchanged without fragmentation issues.

Determine the impact of the MTU mismatch

R2 receives a DBD packet from R1 advertising an MTU of 1500 bytes, which exceeds R2's interface MTU of 1400 bytes. Consequently, R2 drops the packet, causing Master/Slave negotiation to stall endlessly in the ExStart state.

Without ip ospf mtu-ignore enabled, any mismatch in advertised MTU prevents completion of DBD packet exchange.

Anahtar Kavram

OSPF Neighbor States and MTU Mismatch Behavior

Soru 1355Soru →

An engineer is troubleshooting an OSPFv2 neighbor adjacency issue between two directly connected routers. Which two parameters must match on the interconnecting interfaces for an OSPFv2 neighbor relationship to successfully form? (Select TWO.)

Geçerli olan tümünü seçin

Area ID

Hello and Dead timer intervals

OSPF Process ID

OSPF Router ID

Cevabı ve açıklamayı göster

Cevap: Area ID; Hello and Dead timer intervals

Cevap

The parameters that must match for OSPFv2 neighbor adjacency formation are Area ID and Hello and Dead timer intervals.

For two routers to establish an OSPFv2 neighbor adjacency, several parameters exchanged in Hello packets must match: Area ID, Hello and Dead timers, subnet mask/subnet ID, and authentication settings. Area ID and Hello/Dead timers are mandatory matching parameters.

Adım Adım Çözüm

Identify OSPFv2 Hello packet parameter requirements for neighbor formation.

OSPF Hello packets contain parameters that must match (Area ID, Subnet Mask, Hello/Dead timers, Authentication, MTU) and parameters that must be unique (Router ID).

Matching parameters ensure both routers agree on common network boundaries and operational timings.

Evaluate local vs global OSPF settings.

The OSPF Process ID is locally significant to the router, and the Router ID must be unique per router.

Process IDs do not affect protocol negotiation across links, while duplicate Router IDs cause protocol conflicts.

Anahtar Kavram

OSPFv2 Neighbor Adjacency Requirements

Soru 1356Soru →

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

text
Gateway of last resort is not set

192.168.10.0/24 is variably subnetted, 4 subnets, 3 masks
O 192.168.10.0/24 [110/20] via 10.1.1.1, 00:05:12, GigabitEthernet0/0
D 192.168.10.0/26 [90/307200] via 10.1.1.2, 00:12:45, GigabitEthernet0/1
S 192.168.10.0/27 [1/0] via 10.1.1.3
O E2 192.168.10.16/28 [110/20] via 10.1.1.4, 00:01:10, GigabitEthernet0/2

Which next-hop IPv4 address will the router select to forward a packet with a destination IP address of 192.168.10.20?

10.1.1.4

10.1.1.3

10.1.1.2

10.1.1.1

Cevabı ve açıklamayı göster

Cevap: 10.1.1.4

Cevap

The router will select the next-hop address 10.1.1.4.

When a router receives a packet, it compares the destination IP address against all entries in its routing table and selects the route with the longest matching prefix (most specific subnet mask). In this scenario, the destination address 192.168.10.20 matches 192.168.10.0/24, 192.168.10.0/26, 192.168.10.0/27, and 192.168.10.16/28. The /28 route is the most specific match (28 bits), so the router uses its specified next-hop address, 10.1.1.4.

Adım Adım Çözüm

Determine which subnet ranges contain the destination IP address 192.168.10.20.

The destination address 192.168.10.20 falls within 192.168.10.0/24 (.0 - .255), 192.168.10.0/26 (.0 - .63), 192.168.10.0/27 (.0 - .31), and 192.168.10.16/28 (.16 - .31).

All four routes in the routing table match the destination address.

Compare the prefix lengths of all matching routes to apply the Longest Prefix Match rule.

The prefix length of /28 (28 subnet bits) is longer than /27, /26, and /24.

The router always prioritizes the route with the most specific match (longest subnet mask / prefix length), regardless of administrative distance or routing protocol source.

Identify the next-hop IPv4 address associated with the /28 matching entry.

The route for 192.168.10.16/28 specifies the next-hop address 10.1.1.4.

The router forwards packets matching this prefix to 10.1.1.4 out GigabitEthernet0/2.

Anahtar Kavram

Longest Prefix Match Rule

Soru 1357Soru →

A network technician is configuring a newly created WLAN on a Cisco Wireless LAN Controller (WLC) via the web interface. To ensure wireless clients are placed onto the correct IP subnet upon association, the WLAN must be mapped to a specific dynamic interface instead of using the default management interface. Under which tab within the WLANs > Edit menu is this Interface/Interface Group mapping configured?

General tab

Security tab, under the Layer 2 sub-tab

Advanced tab

Security tab, under the AAA Servers sub-tab

Cevabı ve açıklamayı göster

Cevap: General tab

Cevap

The Interface/Interface Group dropdown menu for binding a WLAN to a dynamic interface is located under the General tab in the Cisco WLC GUI.

In the Cisco WLC web GUI, navigating to WLANs > Edit displays the General tab by default. This tab contains fundamental settings including the WLAN Profile Name, broadcast SSID, WLAN Status enablement, and the 'Interface/Interface Group' drop-down list which maps client traffic on that SSID to a specific dynamic interface and associated VLAN.

Adım Adım Çözüm

Identify the required configuration task in the WLC GUI

The goal is to map a WLAN to a dynamic interface/VLAN to ensure correct client IP subnet placement.

By default, new WLANs inherit the management interface unless explicitly configured otherwise.

Locate the primary menu tab for core WLAN identification and interface parameters

In the Cisco WLC web GUI (WLANs > Edit), the General tab houses the Profile Name, SSID, Status enablement checkbox, and the Interface/Interface Group (Gradients) setting.

Interface binding is a core attribute of the WLAN profile configuration located under General settings.

Anahtar Kavram

Cisco WLC GUI WLAN Configuration and Interface Mapping

Tahmini Süre:1m 0s

Soru 1358Soru →

A network administrator executes a command on a Cisco Catalyst switch to inspect details about a newly connected neighbor switch running Link Layer Discovery Protocol (LLDP). The command produces the following output:

text
Switch-Core# show lldp entry Switch-Access-01

Capability codes:
(R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device
(W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other

-----------------------------------------------
Local Interface: Gi1/0/12
Chassis id: 0026.98a1.4b80
Port id: Gi0/1
Port Description: GigabitEthernet0/1
System Name: Switch-Access-01

System Description:
Cisco IOS Software, C3750E Software (C3750E-UNIVERSALK9-M), Version 15.0(2)SE11, RELEASE SOFTWARE (fc3)

Time remaining: 92 seconds
System Capabilities: B, R
Enabled Capabilities: B

Management Addresses:
IP: 192.168.10.5

Based on the output above, which statement accurately describes the connected neighbor device and interface topology?

The neighbor device is connected to local port GigabitEthernet1/0/12 and is operating with Bridge capabilities enabled.

The neighbor device is physically attached to local interface GigabitEthernet0/1 and has Router capabilities enabled.

The local switch sends LLDP advertisement updates to the neighbor every 92 seconds by default.

The LLDP system description TLV signals an active native VLAN mismatch on local interface GigabitEthernet1/0/12.

Cevabı ve açıklamayı göster

Cevap: The neighbor device is connected to local port GigabitEthernet1/0/12 and is operating with Bridge capabilities enabled.

Cevap

The neighbor device is connected to local port GigabitEthernet1/0/12 and is operating with Bridge capabilities enabled.

The output explicitly shows 'Local Interface: Gi1/0/12' as the local switch port and 'Enabled Capabilities: B' as the active bridging capability of the connected neighbor Switch-Access-01.

Adım Adım Çözüm

Identify the local switch interface from the CLI output

The field 'Local Interface: Gi1/0/12' shows that the cable from the neighbor connects directly into port GigabitEthernet1/0/12 on the local switch.

LLDP output explicitly distinguishes between the local receiving interface and the remote neighbor's transmitting port ID.

Examine the capabilities fields for the neighbor device

'System Capabilities: B, R' indicates the device supports both Bridge and Router functions, but 'Enabled Capabilities: B' shows only Bridge capability is active.

System capabilities indicate full hardware/software support, whereas enabled capabilities reflect current operational role.

Verify holdtime vs transmit frequency definitions

'Time remaining: 92 seconds' is the remaining holdtime before the entry expires if no further LLDP updates arrive (default holdtime is 120 seconds, calculated as 30s retransmit x 4 holdtime multiplier).

The time remaining field counts down from the holdtime timer, not the transmission interval.

Anahtar Kavram

Interpreting LLDP Neighbor Details and Capabilities

Tahmini Süre:1m 15s

Soru 1359Soru →

A network administrator is planning a high-density switch-to-server interconnect within a data center that requires a 10GBASE-T copper Ethernet link over an end-to-end cable run of 70 meters. To guarantee full 10 Gbps performance across this distance without exceeding the standard cable specification, which minimum copper twisted-pair cable category must be specified?

Category 5e UTP

Category 6 UTP

Category 6A UTP

Category 5 UTP

Cevabı ve açıklamayı göster

Cevap: Category 6A UTP

Cevap

Category 6A UTP is the correct answer, as it is the minimum specification required to operate 10GBASE-T up to the full standard distance of 100 meters.

The option specifying Category 6A UTP is correct because Category 6A is rated for 500 MHz bandwidth and explicitly guarantees 10GBASE-T performance up to 100 meters (328 feet). At 70 meters, Category 6A is the minimum category that meets the requirement.

Adım Adım Çözüm

Identify the performance requirement and link distance.

The scenario requires 10GBASE-T (10 Gbps Ethernet over twisted-pair copper) across a distance of 70 meters.

Cable categories have specific bandwidth ratings and maximum distance thresholds for higher-speed Ethernet standards.

Evaluate standard Category 6 limitations for 10GBASE-T.

Category 6 cable can run 10GBASE-T, but only for distances between 37 and 55 meters max due to alien crosstalk issues at higher frequencies (up to 250 MHz).

A 70-meter run exceeds the maximum 55-meter operating envelope for Category 6 at 10 Gbps.

Select the minimum category that satisfies the full 70-meter distance.

Category 6A (Augmented Category 6) operates at frequencies up to 500 MHz and features stricter alien crosstalk specifications, supporting 10GBASE-T for up to 100 meters.

Category 6A fulfills the minimum technical requirement for a 70-meter 10GBASE-T connection.

Anahtar Kavram

Copper Ethernet Cabling Standards and 10GBASE-T Distance Limits

Soru 1360Soru →

Three Cisco routers (R1, R2, and R3) are connected to the same Layer 2 Ethernet switch on the 10.1.1.0/24 subnet and configured in OSPFv2 Area 0. Router R1 completes OSPF initialization first and is successfully elected as the Designated Router (DR). To optimize resource utilization, the network administrator explicitly configures the interface command `ip ospf priority 0` on GigabitEthernet0/0 on both R2 and R3.

After all OSPF processes converge, what neighbor state will be displayed when issuing the `show ip ospf neighbor` command on router R2 specifically for the neighbor entry corresponding to router R3?

FULL/DROTHER

2WAY/DROTHER

EXSTART/DR

INIT/DROTHER

Cevabı ve açıklamayı göster

Cevap: 2WAY/DROTHER

Cevap

The neighbor state between R2 and R3 will be 2WAY/DROTHER.

On a broadcast multiaccess network (such as Ethernet), routers only establish FULL adjacencies (exchanging link-state databases) with the Designated Router (DR) and Backup Designated Router (BDR). Routers configured with an OSPF priority of 0 cannot become DR or BDR (they remain DROTHERs). When two DROTHER routers discover each other via Hello packets, they verify bi-directional communication and remain stably in the 2WAY/DROTHER state.

Adım Adım Çözüm

Analyze OSPF interface priority settings for R2 and R3.

Setting 'ip ospf priority 0' disables a router from participating in DR/BDR election, forcing both R2 and R3 into DROTHER status on the broadcast network.

Routers with an OSPF priority of 0 can never become a DR or BDR.

Evaluate OSPF adjacency requirements on broadcast multiaccess networks.

Full adjacencies are formed only between DROTHER routers and the DR/BDR. Routers that are both DROTHERs form relationships that stop at 2-WAY state.

This behavior minimizes flooding overhead and database synchronization traffic on multiaccess media.

Determine the output of the show command on R2 for R3.

The neighbor relationship successfully reaches bi-directional communication, yielding a state of 2WAY/DROTHER.

Both routers hear each other's Hellos (2-WAY), but neither router is a DR or BDR, so no LSA exchange takes place between them.

Anahtar Kavram

OSPF Adjacency Formation on Multiaccess Networks and Priority 0 Behavior

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