200-901 Network Fundamentals — All Questions With Answers

A network engineer is troubleshooting slow connectivity between two sites connected via a WAN link. The engineer suspects packet loss due to collisions. Which interface counter should be examined to confirm this?

Question 2hardmultiple choice

A DevOps team is deploying a containerized application across multiple hosts. They need to ensure that traffic between containers on the same host is isolated from other tenants. Which network implementation best meets this requirement?

Question 3easymultiple choice

Read the full network assurance explanation →

An engineer notices that a switch port configured as an access port in VLAN 10 is not forwarding traffic. The switch shows the port is up/up. What is the most likely cause?

Question 4mediummultiple choice

A network administrator is configuring SNMPv3 on a router for secure monitoring. Which combination of parameters is required to ensure authentication and encryption?

Question 5hardmultiple choice

Read the full DNS explanation →

During a network migration, an engineer needs to replace a legacy core switch with a new one without disrupting the existing STP topology. The new switch supports RSTP and will be connected via two trunk links. Which configuration should be applied to the new switch to prevent it from becoming the root bridge?

Question 6easymultiple choice

A technician needs to verify the IP address of a remote server using DNS. Which command should be used on a Cisco IOS device?

Question 7mediummultiple choice

A network engineer is designing a data center network with leaf-spine topology. The requirement is to minimize latency and maximize bandwidth for east-west traffic. Which type of links should be used between leaf and spine switches?

Question 8hardmultiple choice

An organization uses Cisco ISE for network access control. A user reports inability to access the network. The switch port shows the authenticator state as 'connecting'. What does this indicate?

Question 9mediummulti select

Which TWO statements are true about VXLAN? (Choose two.)

Question 10hardmulti select

Which THREE factors influence the convergence time of OSPF in a large enterprise network? (Choose three.)

Question 11easymulti select

Which TWO functions are performed by the data plane in a network device? (Choose two.)

Question 12mediummultiple choice

An engineer configures a trunk port as shown. A device connected to this port sends an untagged frame. Which VLAN will the switch associate the frame with?

Exhibit

Refer to the exhibit.
```
interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk native vlan 99
 switchport trunk allowed vlan 10,20,30
```

Question 13hardmultiple choice

Open the full BGP breakdown →

Based on the routing table, what type of OSPF route is the default route (0.0.0.0/0)?

Exhibit

Refer to the exhibit.
```
R1# show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is 10.0.0.1 to network 0.0.0.0

O*E2 0.0.0.0/0 [110/1] via 10.0.0.1, 00:00:34, GigabitEthernet0/0
O    10.0.0.0/8 [110/2] via 10.0.0.1, 00:00:34, GigabitEthernet0/0
O    172.16.0.0/16 [110/3] via 192.168.1.1, 00:00:34, GigabitEthernet0/1
C    192.168.1.0/24 is directly connected, GigabitEthernet0/1
```

Question 14hardmultiple choice

A company has a three-tier data center architecture with access, aggregation, and core layers. The network team is migrating to a leaf-spine architecture to support increasing east-west traffic. The current network uses STP for loop prevention, and the team wants to eliminate STP in the new design. They plan to use VXLAN overlays with BGP EVPN for control plane. During a pilot deployment, the team notices that some legacy servers that rely on traditional VLANs are not reachable across the new fabric. The servers are connected to access switches that are part of the leaf layer. The access switches are configured as VXLAN tunnel endpoints (VTEPs) but the legacy servers are still using traditional VLANs. The team needs to ensure connectivity between the legacy VLAN-based servers and the new VXLAN-based network. What is the best approach to integrate these legacy servers without changing their configuration?

Question 15mediummultiple choice

A university campus network uses Cisco switches with 802.1X for wired authentication. Recently, users in a dormitory report intermittent connectivity: they can connect initially but are disconnected after a few minutes. The network team checks the switch logs and sees messages like 'Authentication failure for MAC address xxxx.xxxx.xxxx on port GigabitEthernet1/0/5' but the users claim they are using valid credentials. The same users can connect from other ports without issues. The port configuration for Gi1/0/5 is: switchport mode access, authentication port-control auto, dot1x pae authenticator, authentication periodic, authentication timer reauthenticate 3600. The team suspects a misconfiguration. What is the most likely cause of the intermittent disconnections?

Question 16mediummulti select

A network engineer is troubleshooting an issue where hosts in VLAN 100 cannot reach a server at 10.1.1.100. The switch interfaces are configured as access ports in VLAN 100, and the default gateway is 10.1.1.1. The engineer checks the switch and finds that the ARP table does not contain the server's MAC address. Which two actions should the engineer take to resolve the issue? (Choose two.)

Question 17hardmultiple choice

Refer to the exhibit. A switch is configured with the shown trunk port. After connecting the uplink, the switch logs show repeated 'errdisable' state transitions on this port. The core switch is configured with the same allowed VLAN list. Which configuration change is most likely to resolve the issue?

Exhibit

Refer to the exhibit.

"""
interface GigabitEthernet0/1
 description Uplink to Core
 switchport mode trunk
 switchport trunk allowed vlan 10,20,30
 spanning-tree portfast trunk
"""

Question 18easymulti select

A network administrator is deploying a new application that requires high availability and load balancing across multiple servers. The servers are connected to a pair of switches that use StackWise virtual technology. The application team requests that the servers be configured with NIC teaming in active-active mode. Which two requirements must be met for this configuration to work correctly? (Choose two.)

Question 19mediumdrag order

Drag and drop the steps to configure a Cisco switch for remote management (SSH) into the correct order.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 20mediummatching

Match each Cisco platform to its primary use case.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Intent-based networking management

Cloud-managed network administration

Collaboration and messaging integration

Unified infrastructure management

Application performance monitoring

Question 21easymultiple choice

An engineer needs to identify which hosts are reachable in a 10.0.0.0/24 network using an automated script that does not require any credentials on the target devices. Which protocol is best suited for this task?

Question 22mediummultiple choice

Read the full REST/YANG explanation →

A developer is writing an application that needs to send a large amount of data reliably over a network. Which transport layer protocol should the developer use?

Question 23hardmultiple choice

A network automation script uses RESTCONF to configure a router. The script receives an HTTP 409 Conflict response. What is the most likely cause?

Question 24easymultiple choice

An engineer wants to verify that a switch port is configured as an access port in VLAN 10. Which command provides this information?

Question 25mediummultiple choice

A company has multiple subnets. A device in subnet 192.168.1.0/24 needs to communicate with a device in subnet 192.168.2.0/24. What is required for this communication?

Question 26hardmultiple choice

Study the full IPv6 explanation →

An application sends a packet with destination IP 10.0.0.10. The sending host's routing table has a default gateway of 10.0.0.1. The host's ARP cache is empty. What is the next step after the host determines the packet should go to the default gateway?

Question 27easymultiple choice

Which IPv6 address type is equivalent to a private IPv4 address?

Question 28mediummultiple choice

Review the full routing breakdown →

An engineer needs to transfer a router configuration file to a server in the same network using a simple protocol that does not require authentication. Which protocol is best?

Question 29hardmultiple choice

A developer is building a chat application that requires low-latency communication, and occasional packet loss is acceptable. Which transport protocol should the developer choose?

Question 30easymulti select

Which TWO of the following are examples of application layer protocols?

Question 31mediummulti select

Which TWO of the following are common causes of VLAN connectivity issues?

Question 32hardmulti select

Review the full routing breakdown →

Which THREE of the following are valid methods to automatically assign IP addresses to network hosts?

Question 33mediummultiple choice

Based on the routing table, what is the administrative distance of the route to 192.168.1.0/24?

Exhibit

Router# show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, i - IS-IS
       su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is 10.0.0.2 to network 0.0.0.0

      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        10.0.0.0/24 is directly connected, GigabitEthernet0/0
L        10.0.0.1/32 is directly connected, GigabitEthernet0/0
      192.168.1.0/24 [120/1] via 10.0.0.2, 00:00:23, GigabitEthernet0/0
S*      0.0.0.0/0 [1/0] via 10.0.0.2

Question 34hardmultiple choice

Based on the NAT translation table, what type of NAT is being used?

Exhibit

R1# show ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
icmp 203.0.113.10:1   10.0.0.1:1         192.0.2.5:1        192.0.2.5:1
tcp 203.0.113.10:80   10.0.0.1:80        192.0.2.5:80       192.0.2.5:80

Question 35easymultiple choice

What does a TTL of 128 indicate about the destination host?

Exhibit

C:\> ping 192.168.1.1

Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.1.1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms

Question 36easymultiple choice

A network administrator is troubleshooting a connectivity issue. A PC with IP address 192.168.1.10/24 cannot ping a server at 192.168.1.20/24. Both are on the same VLAN and connected to the same switch. What is the most likely cause of the issue?

Question 37mediummultiple choice

Read the full Ansible explanation →

A company uses a /24 subnet for its office LAN. The network must accommodate 30 hosts per VLAN. Which subnet mask would be most efficient for each VLAN while minimizing wasted IP addresses?

Question 38hardmultiple choice

A DevOps engineer is automating network device configuration using Ansible. The playbook must retrieve the MAC address table from a Cisco switch. Which protocol should the engineer use to fetch this data?

Question 39easymultiple choice

A network technician runs the command 'ping 8.8.8.8' from a workstation and receives 'Reply from 192.168.1.1: Destination host unreachable.' What does this indicate?

Question 40mediummultiple choice

An application developer is designing a microservice that communicates over HTTP. The service must guarantee that the request is processed exactly once. Which HTTP method should be used to ensure idempotency?

Question 41hardmultiple choice

A network engineer is configuring a Cisco switch to support LLDP-MED for VoIP phones. Which command is required to enable LLDP globally on the switch?

Question 42easymultiple choice

Read the full DHCP explanation →

A developer needs to send a diagnostic request to a network device to verify if it supports a specific MIB object. Which protocol and operation should be used?

Question 43mediummultiple choice

A company has a DHCP server that assigns IP addresses from a scope of 192.168.10.0/24. A new device receives IP 192.168.10.100/24 but cannot access the internet. The default gateway is 192.168.10.1. What is the most likely issue?

Question 44hardmultiple choice

Read the full REST/YANG explanation →

An automation script uses the Cisco IOS XE REST API to modify the running configuration. The script sends a PUT request to /restconf/data/Cisco-IOS-XE-native:native/interface/GigabitEthernet=1/0/1/ip/address. The response returns 405 Method Not Allowed. What is the most likely reason?

Question 45easymulti select

Which TWO of the following are functions of the transport layer in the OSI model? (Choose two.)

Question 46mediummulti select

Which THREE of the following are valid JSON data types? (Choose three.)

Question 47hardmulti select

Which TWO of the following features are provided by Cisco DNA Center but NOT by Cisco Prime Infrastructure? (Choose two.)

Question 48easymultiple choice

Refer to the exhibit. A PC is connected to interface GigabitEthernet0/1 on a Cisco switch. The PC is in VLAN 10. What is the purpose of the 'spanning-tree portfast' command on this interface?

Exhibit

Refer to the exhibit.
```
interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 spanning-tree portfast
```

Question 49mediummultiple choice

Refer to the exhibit. A switch has the VLAN configuration shown. If a device is connected to interface Gi0/3 and another to Gi0/5, can they communicate if the switch is not configured with any inter-VLAN routing?

Exhibit

Refer to the exhibit.
```
Switch# show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi0/1, Gi0/2
10   Engineering                      active    Gi0/3, Gi0/4
20   Marketing                        active    Gi0/5, Gi0/6
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
1005 trnet-default                    act/unsup
```

Question 50hardmultiple choice

Refer to the exhibit. A router has the routing table shown. A packet arrives at GigabitEthernet0/0 with destination IP 8.8.8.8. What will the router do?

Exhibit

Refer to the exhibit.
```
Router# show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is 10.0.0.1 to network 0.0.0.0

     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       10.0.0.0/30 is directly connected, GigabitEthernet0/0
L       10.0.0.2/32 is directly connected, GigabitEthernet0/0
     192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks
C       192.168.1.0/24 is directly connected, GigabitEthernet0/1
L       192.168.1.1/32 is directly connected, GigabitEthernet0/1
S*   0.0.0.0/0 [1/0] via 10.0.0.1
```

Question 51easymultiple choice

A network engineer is troubleshooting a connectivity issue between two hosts in different VLANs on the same switch. The hosts are in VLAN 10 and VLAN 20, respectively. The switch has an SVI for each VLAN and IP routing is enabled. Which command should be used to verify that the switch is forwarding traffic between the VLANs?

Question 52easymultiple choice

A company is designing a new branch network. They want to segment traffic into separate broadcast domains to improve security and reduce broadcast traffic. Which technology should be used to achieve this?

Question 53easymultiple choice

A network administrator needs to assign IP addresses to 50 hosts in a subnet. Which subnet mask provides the minimum required number of usable addresses while minimizing waste?

Question 54mediummultiple choice

A network engineer notices that after a link failure, traffic to a server on a different VLAN is intermittent. The network uses Rapid PVST+. The switch connecting the server is a root bridge for that VLAN. What is the most likely cause of the intermittent connectivity?

Question 55mediummultiple choice

A network administrator is configuring OSPF on a router and wants to ensure that routes from area 0 are propagated to area 1, but area 1 should not see specific inter-area routes. Which OSPF feature should be used?

Question 56mediummultiple choice

Read the full EtherChannel explanation →

A user reports that they can ping the IP address of the default gateway but cannot ping a server on a different subnet. The administrator checks the ARP table on the user's PC and sees an incomplete entry for the server's IP. What is the most likely cause?

Question 57hardmultiple choice

A network engineer is configuring EtherChannel between two switches. The switches are connected via four links. The engineer wants to load balance traffic based on source and destination IP addresses. Which configuration command should be used on Cisco IOS?

Question 58hardmultiple choice

Study the full IPv6 explanation →

An IPv6-enabled host is trying to discover the MAC address of another host on the same link. The host knows the destination IPv6 address but does not have a corresponding entry in the neighbor cache. Which protocol and message type does the host use?

Question 59hardmultiple choice

Open the full BGP breakdown →

A network administrator is troubleshooting BGP path selection for a route received from two different ISPs. The routes have the same local preference and AS-path length, but one route has a shorter MED value. Which route will be preferred?

Question 60easymulti select

Which TWO are benefits of using VLANs in a network? (Choose two.)

Question 61mediummulti select

Which THREE are characteristics of OSPF? (Choose three.)

Question 62hardmulti select

Which TWO are components of a REST API request? (Choose two.)

Question 63easymultiple choice

A network engineer is configuring a new switch and needs to ensure that frames from VLAN 10 and VLAN 20 are isolated on the same trunk link to another switch. Which IEEE standard should be configured on the trunk interfaces?

Question 64mediummultiple choice

During a network outage, a technician notices that hosts in VLAN 10 cannot reach the default gateway at 192.168.10.1, but hosts in VLAN 20 can. The switch interfaces are up, and the router is configured with subinterfaces. What is the most likely cause?

Question 65hardmultiple choice

A DevOps team is automating network configuration using Ansible. They want to push a new VLAN configuration to a switch but ensure that only one switch is updated at a time to avoid network disruption. Which Ansible strategy or feature should they use?

Question 66easymultiple choice

A network administrator needs to verify that a switch port is configured as an access port and assigned to VLAN 30. Which command should be used on a Cisco IOS switch?

Question 67mediummultiple choice

A company is deploying a new application that requires low-latency communication between servers in the same data center. The network team is designing a leaf-spine architecture. What is the primary advantage of this topology over a traditional three-tier design?

Question 68hardmultiple choice

An engineer is troubleshooting packet loss between two hosts on different subnets. The traceroute shows that packets reach the first hop router but then stop. The router's ARP table shows an incomplete entry for the next-hop IP address. What is the most likely cause?

Question 69easymultiple choice

Open the full BGP breakdown →

A network engineer needs to allow HTTPS traffic from the internet to an internal web server. Which type of firewall rule should be applied on the perimeter firewall?

Question 70mediummultiple choice

A network administrator is asked to reduce the size of the routing table on a core router. The router currently has many /24 routes learned via BGP. Which technique will most effectively reduce the number of routes without losing reachability to all subnets?

Question 71mediummulti select

Study the full IPv6 explanation →

Which TWO of the following are valid reasons to use a trunk link between two switches? (Select exactly two.)

Question 72hardmulti select

Which THREE of the following are characteristics of IPv6? (Select exactly three.)

Question 73easymulti select

Which THREE of the following are layers in the OSI model? (Select exactly three.)

Question 74hardmultiple choice

You are a network engineer at a financial services company. The network uses OSPF as the IGP, and all routers are in area 0. The core network consists of four routers (R1, R2, R3, R4) connected in a full mesh with GigabitEthernet links. The OSPF cost is set to 1 on all interfaces. Recently, a new application was deployed that requires low jitter and deterministic paths between two servers: Server A connected to R1 and Server B connected to R4. During peak hours, you notice that traffic between the servers is using the path R1->R3->R4 instead of R1->R2->R4, causing higher latency due to congestion on R3. OSPF metrics reflect equal cost to both paths (cost 2 each). You need to enforce that traffic from Server A to Server B always uses the path through R2 without changing the topology or adding additional hardware. Which action should you take?

Question 75easymultiple choice

You are troubleshooting connectivity for a remote branch office. The branch router (BR) connects to the head office router (HQ) via a point-to-point T1 link. The HQ router is also connected to the internet via a separate interface. Users at the branch can access the internet but cannot reach servers at the head office (subnet 10.10.10.0/24). You run 'show ip route' on BR and see a default route pointing to HQ's IP address, but no specific route for 10.10.10.0/24. The HQ router has a connected route for that subnet. On HQ, you see that the interface towards BR is up/up, and you can ping the BR's interface IP. What is the most likely cause of the issue?

Question 76mediummultiple choice

Study the full Python automation breakdown →

You are deploying a new data center network using Cisco Nexus switches. The design uses Virtual Port Channel (vPC) to provide redundancy and increased bandwidth to servers with dual-homed NICs. The two vPC peer switches are NX1 and NX2, and they are connected via a peer-link. The servers are configured with active/standby NIC teaming. After the deployment, you notice that some ARP requests from servers are not being responded to, leading to connectivity issues. Analysis shows that when a server sends an ARP request for its default gateway (which is a virtual IP on the vPC), only one of the peer switches responds, but the response does not reach the server intermittently. The vPC is correctly configured, and the peer-gateway feature is enabled. What is the most likely cause?

Question 77mediummultiple choice

You manage a network that uses a mix of Cisco IOS and IOS-XE devices. The company wants to implement network automation using RESTCONF and YANG. You have configured RESTCONF on a branch router running IOS-XE 16.12. You can successfully retrieve the interface configuration using a GET request from a Python script. However, when you try to modify the description of an interface using a PATCH request, you receive a 405 Method Not Allowed error. The script uses basic authentication over HTTPS. The URL is correct, and the YANG data payload is valid. What is the most likely reason for the failure?

Question 78mediummulti select

Read the full DNS explanation →

A network engineer needs to create a new subnet that can support at least 50 usable host addresses for a development environment. Which TWO subnet masks would meet this requirement? (Choose two.)

Question 79easymultiple choice

A developer is trying to access an internal corporate web API at http://api.internal.company.com from their workstation, which has the IP configuration: IP address 192.168.1.100, subnet mask 255.255.255.0, default gateway 192.168.1.1, and DNS server 192.168.1.2. The developer can ping the DNS server (192.168.1.2) successfully, but when they try to curl the API endpoint, the command times out. The developer also confirms that the API server is up and reachable from other devices on the same subnet. Which action should the developer take to resolve this issue?

Question 80hardmultiple choice

A network automation engineer is using a Python script with the requests library to configure VLAN 100 on a Cisco Catalyst 9300 switch via the REST API. The script sends a PUT request to https://switch-ip/restconf/data/Cisco-IOS-XE-native:native/vlan. The response returns a 201 Created, but subsequent checks show VLAN 100 is not present in the running configuration. The switch's management interface is in VLAN 99 with IP 10.10.99.10/24, and the engineer's workstation is on a different subnet (10.10.88.0/24). The switch has the following relevant configuration: ip default-gateway 10.10.99.1, and a route for 10.10.88.0/24 via 10.10.99.1. The engineer also verified that the REST API credentials are correct and that the switch's HTTP server is enabled. Which action should the engineer take to resolve the issue?

Question 81mediummulti select

Which TWO statements about VLAN trunking are true?

Question 82hardmultiple choice

Refer to the exhibit. Both switches are configured with EtherChannel. Which statement is true about VLAN traffic across the trunk?

Exhibit

SwitchA# show running-config interface port-channel1
!
interface Port-channel1
 switchport mode trunk
 switchport trunk allowed vlan 1-100,200

SwitchB# show running-config interface port-channel1
!
interface Port-channel1
 switchport mode trunk
 switchport trunk allowed vlan 1-50,100-199

Question 83easymultiple choice