Show Command Output Questions

The EtherChannel is using PAgP.

Why it fails: The EtherChannel is using PAgP. The output clearly shows the EtherChannel protocol as LACP (Link Aggregation Control Protocol, IEEE 802.3ad), not PAgP (Port Aggregation Protocol, Cisco proprietary). In the 'show etherchannel summary' output, the 'Protocol' column would list LACP, confirming that PAgP is not in use. PAgP and LACP are mutually exclusive, so this option is factually incorrect.

Port Gi0/3 is bundled in the channel.

Why it fails: Port Gi0/3 is bundled in the channel. In 'show etherchannel summary', each member port is assigned a flag: 'P' means the port is bundled and actively participating in the channel, while 'D' means the port is down or administratively down. Gi0/3 shows the flag 'D', not 'P', so it is not part of the active EtherChannel bundle. Only ports with the 'P' flag are actively forwarding traffic.

The port-channel is a Layer 3 interface.

Why it fails: The port-channel is a Layer 3 interface. The output identifies the port-channel's layer type via a flag on the logical interface: 'S' signifies a Layer 2 port-channel, whereas 'R' would denote a Layer 3 routed port-channel. Since the flag shown is 'S', the EtherChannel is operating at Layer 2, making this statement incorrect. A Layer 3 port-channel would require an 'R' flag and an IP address configured on the logical interface.

The routers are configured with a different enable secret that does not match the one in the Ansible vault.

Why it fails: An incorrect enable secret in the Ansible vault would produce an immediate authentication failure — IOS would return '% Bad secrets' or 'Enable password incorrect' — causing the task to error out, not hang while waiting for a prompt. The indefinite wait suggests Ansible never even attempted to send the enable command because it did not know to use enable as the become method. Thus the failure is a missing escalation configuration, not a credential mismatch.

The SSH key exchange is taking longer than the default 12-second timeout.

Why it fails: SSH key exchange and the default 12-second connection timeout occur during transport establishment, before the CLI session is interactive; a problem there would surface as an unreachable host or 'SSH Error: timeout' without ever reaching a prompt. The described symptom specifically involves waiting for a shell/privilege prompt after the SSH session is already up, so it cannot be caused by key exchange latency. Therefore it is a post-authentication escalation issue, not a transport-layer timeout.

The ios_command module requires a different privilege level to execute 'show ip route'.

Why it fails: The ios_command module does not enforce privilege levels; the device does, and 'show ip route' would at worst produce an IOS authorization error such as 'Invalid input' if executed from a restricted view, not an indefinite wait. The timeout shown indicates the session was never elevated to privileged EXEC mode, so the command was never actually sent. That points to the missing become_method setting, not to a requirement that the command run at a different privilege level.

The AS-path contains the local AS number.

Why it fails: This is incorrect. While an AS-path containing the local AS number can cause routes to be rejected due to loop prevention, the typical symptom is routes not being received at all or being marked as invalid, not the specific 'received but not valid' status. The most common cause for 'not valid' is next-hop unreachability.

BGP synchronization is enabled.

Why it fails: This is incorrect. BGP synchronization is a legacy feature that requires the route to be in the IGP before it is advertised. In modern networks, synchronization is disabled by default. Even if enabled, it affects advertisement, not the validity of received routes in the BGP table.

The maximum-prefix limit has been exceeded.

Why it fails: This is incorrect. Exceeding the maximum-prefix limit typically causes the BGP session to reset or routes to be withdrawn, not to be marked as 'not valid' in the BGP table. Routes would likely be removed entirely, not just marked invalid.

The interface is configured as an access port.

Why it fails: The show interfaces trunk output explicitly lists the Administrative Mode as 'trunk' and the Operational Mode as 'trunk', which directly contradicts the assertion that the interface is configured as an access port. An access port would have an administrative mode of 'static access' or 'dynamic auto' and would not appear in the trunk output. Therefore, this conclusion is unsupported by the command output.

The native VLAN is tagged with 802.1Q.

Why it fails: Actually, native VLAN tagging is enabled, meaning the native VLAN is tagged, but the statement is ambiguous. However, the correct interpretation is that native VLAN tagging is enabled, but the question asks what can be concluded. Option B is more directly supported.

All VLANs except 2-1001 are pruned.

Why it fails: The line 'Pruning VLANs Enabled: 2-1001' indicates that VLANs 2 through 1001 are eligible for pruning, meaning the switch may remove them from the trunk for load balancing if the neighbor does not use them. It does not state that these VLANs are actually being pruned, nor does it imply that all other VLANs are pruned. The phrasing 'except 2-1001 are pruned' inverts the correct meaning, confusing eligibility with active pruning.

All IP SLA operations are active.

Why it fails: The asterisk (*) in the output of `show ip sla` is the indicator that an operation is actively running, and it appears exclusively next to operation ID 4. Every other operation listed lacks this marker, which means they are either configured but not scheduled, or they are in an inactive or stopped state. Therefore, interpreting all operations as active is a misreading of the state column and would be incorrect for this output.

IP SLA operation 3 has failed.

Why it fails: Operation 3 is reported with a status of 'Success', which is the direct opposite of a failed state. In IP SLA output, a failed operation would display a status such as 'Timeout', 'Over threshold', or a non-zero return code. Since the output explicitly shows 'Success' for operation 3, it has not failed; it is operating normally and generating expected results.

IP SLA operation 1 has the highest round-trip time.

Why it fails: The 'Last' column in IP SLA output records the most recent round-trip time (RTT) measurement, and operation 1 shows a value of 1, which is the lowest number among the listed operations. Assuming this is a common unit like seconds or milliseconds, a value of 1 cannot be the highest RTT. Furthermore, the 'Last' column may reflect a different metric depending on the operation type, but in no reasonable interpretation does operation 1 represent the highest round-trip time.

Both neighbors are using MD5 authentication.

Why it fails: The EIGRP neighbor table command output (show ip eigrp neighbors) does not include any authentication-related fields, such as the key ID or hash algorithm, because authentication is configured under the EIGRP process or interface, not displayed in the neighbor adjacency table. A stable neighbor relationship can exist with or without authentication, and this output offers no evidence to determine whether MD5 or any other authentication method is in use. Therefore, the statement about MD5 authentication is unsupported by the provided data.

Neighbor 192.168.1.2 has a higher metric than 10.1.1.2.

Why it fails: The EIGRP neighbor table lists neighbor IP addresses along with hold time, uptime, SRTT, RTO, queue count, and sequence number, but it does not display metric values for routes learned from those neighbors. Metrics are stored and shown in the EIGRP topology table (show ip eigrp topology), which contains the composite metric and vector metrics for each route. Without topology table output, there is no basis to claim that 192.168.1.2 has a higher metric than 10.1.1.2.

Router R1 is using EIGRP named mode.

Why it fails: The header 'EIGRP-IPv4 Neighbors for AS(100)' is the format used for classic EIGRP configuration, which is created with the 'router eigrp 100' global configuration command. In named mode (EIGRP named configuration), the output includes VRF and address-family context, such as 'EIGRP-IPv4 Neighbors for VRF(NAME)' or 'EIGRP-IPv4 Neighbors for AS(100) VRF(NAME)' when using address-family configuration. The absence of a VRF or address-family label in the header indicates the router is running classic EIGRP mode, not named mode.

All ports shown are in trunk mode.

Why it fails: Trunk ports would appear in 'show interfaces trunk' or be listed with 'trunk' in 'show vlan brief' (some IOS versions show trunk ports as 'trunk' in the Ports column). Here, only access ports are listed.

VLANs 1002-1005 are active and supported.

Why it fails: The VLANs 1002–1005 are shown in the 'act/unsup' state, meaning they are active but unsupported on this hardware platform. These are reserved FDDI and Token Ring VLANs, and the 'unsup' status indicates the switch cannot actually process them for user data forwarding. Therefore, the claim that they are both active and supported is false; their being active in the VLAN database does not imply they are operationally supported.

VLAN 20 has no ports assigned.

Why it fails: VLAN 20 is not without ports because the Ports column for VLAN 20 explicitly shows Gi0/6 and Gi0/7 assigned. The statement that VLAN 20 has no ports assigned misreads the output, which lists those two interfaces as active access members in that VLAN. Since interfaces Gi0/6 and Gi0/7 appear under VLAN 20, this option is incorrect.

Telnet from 10.0.0.0/8 is denied.

Why it fails: Entry 10 permits Telnet from 10.0.0.0/8.

SSH from 172.16.0.0/16 is denied.

Why it fails: Entry 30 permits SSH from 172.16.0.0/16.

All traffic is permitted.

Why it fails: Telnet and SSH from unauthorized sources are denied.

The OSPF adjacency between PE1 and CE1 is down.

Why it fails: An OSPF adjacency failure would prevent the PE from learning CE routes in the first place, so the VRF routing table would not contain the missing prefix as an OSPF route. The scenario explicitly indicates the route is present in the VRF, which proves that the OSPF hello/DBD/LSU process has completed and the neighbor is in the Full state. Therefore, an adjacency-down condition cannot explain why an already-installed VRF route is absent from BGP.

The VRF forwarding table on PE1 is full.

Why it fails: A full VRF forwarding table is an FIB/CEF resource issue and would affect how packets are forwarded or whether a new route can be programmed into the data plane, not whether that route exists in the BGP VPNv4 table. In L3VPN operation, VPNv4 advertisement is driven by the VRF routing table and the redistribution policy under BGP, not by the size or capacity of the VRF forwarding table. If the route already appears in the VRF RIB, there is no capacity-related reason it cannot also be redistributed into BGP.

MPLS LDP is not enabled on the PE1-CE1 link.

Why it fails: LDP on the PE-CE link is nonsensical in a standard L3VPN design because LDP typically allocates labels for IGP routes across the MPLS core (P-to-P and PE-to-P interfaces), while the PE-to-CE link runs a plain IP routing protocol such as OSPF. VPNv4 prefixes are carried end-to-end in MP-BGP, which also allocates the inner VPN label; any core label needed for transport is handled by LDP or segment routing inside the service provider backbone. Missing LDP on the access link therefore has nothing to do with the failure to redistribute OSPF VRF routes into BGP on PE1.

VRF CUSTOMER-A is not using BGP for routing

Why it fails: This statement is incorrect because the routing table for VRF CUSTOMER-A explicitly includes a BGP entry. The 'B' code in the output is standard for Border Gateway Protocol routes, and the presence of this entry with a valid next-hop (192.168.1.2) proves BGP is operational for this VRF. BGP is often configured under 'router bgp' with an address-family ipv4 (or ipv6) vrf CUSTOMER-A to enable per-VRF route exchange. Therefore, claiming BGP is not used contradicts the direct evidence from the show ip route vrf output.

The default route is learned via BGP

Why it fails: The gateway of last resort being 10.0.1.1 does not mean the default route was learned via BGP. A default route in the routing table is shown as 0.0.0.0/0, and its source can be static configuration, connected, or a dynamic protocol such as OSPF or EIGRP. The BGP entry for 10.0.2.0/24 is a distinct, non-default prefix, and there is no indication in the output that a BGP-learned default route exists. It is equally plausible the default route is a static route pointed to 10.0.1.1 originating from the service provider or local configuration.

GigabitEthernet0/0.100 is not associated with VRF CUSTOMER-A

Why it fails: This is incorrect because the directly connected route for GigabitEthernet0/0.100 appears within the VRF CUSTOMER-A routing table. If the subinterface had not been associated with the VRF, its connected network would reside in the global routing table instead. A subinterface is placed into a VRF by issuing the 'vrf forwarding CUSTOMER-A' command under the interface configuration, which tags all subsequently learned routes on that interface with the VRF instance. Therefore, the presence of that interface's connected routes in the VRF table is definitive proof of association.

Both interfaces have the same metric weight for bandwidth and delay.

Why it fails: The show output for these interfaces only reports interface-level attributes such as bandwidth and delay; EIGRP metric weights (k-values) are configured globally under the EIGRP process via the metric weights command and are not interface-specific. Consequently, comparing metric weights for Gi0/0 and Gi0/1 is not possible from this output, and the statement that both interfaces have the same metric weight is an unsupported and incorrect inference.

Interface Gi0/1 is configured as a passive interface.

Why it fails: The command output includes a Passive interface field for each interface, and for Gi0/1 it explicitly states No. A passive interface in EIGRP would stop sending Hello packets and would not establish neighbors, leaving the interface in a passive state; the output would then indicate Yes. Therefore, the assertion that Gi0/1 is passive directly contradicts the displayed interface status and is wrong.

EIGRP authentication is enabled on both interfaces.

Why it fails: The output clearly lists Authentication: None for both interfaces, which means no MD5 or HMAC-SHA authentication key is configured for EIGRP on Gi0/0 or Gi0/1. If EIGRP authentication were enabled, the interface output would show the authentication mode (e.g., MD5 or HMAC-SHA-256) and associated key chain. Since the field is None, both interfaces are operating without authentication, making the statement false.

30 seconds

Why it fails: The output explicitly lists Frequency (seconds): 60, so 30 seconds contradicts the configured value. Thirty seconds is tempting because it is half the frequency and matches nothing else in the entry, whereas the correct figure is read directly from the Frequency field, not derived from timeout or threshold values.

120 seconds

Why it fails: 120 seconds appears nowhere in the output; Frequency (seconds) is 60. Doubling the value is tempting if you misread the two-hour distribution statistics window or assume a 60-second timeout plus 60-second frequency, but the frequency field is the authoritative source.

5000 milliseconds

Why it fails: 5000 milliseconds is the Operation timeout and Threshold value, not the frequency; the Frequency field states 60 seconds. The timeout is tempting because it is the largest millisecond figure shown, but it governs how long a single probe waits for a reply, not how often probes are sent.

Write a custom parser that handles each router's output format individually.

Why it fails: A custom parser written for each router's output format is unsustainable in a heterogeneous network because every vendor, platform, and software version can introduce subtle differences in column headers, spacing, and line wrapping. This approach also duplicates logic and creates a maintenance burden whenever OS updates occur, and it does not scale as new device types are added. In contrast, TextFSM templates separate the parsing rules from the Python code, so the same template can be reused across many devices.

Use the 'split()' method to tokenize each line and then extract the relevant fields by position.

Why it fails: Using the split() method to tokenize each line and extract fields purely by position assumes a fixed column order and consistent whitespace, which is rarely guaranteed in real 'show ip interface brief' output. When interfaces wrap onto multiple lines, protocols show additional flags, or the header is localized, the indexes shift and the parser silently returns wrong data. TextFSM avoids this by matching named fields with regex rules rather than relying on positional offsets.

Use the 're' module with a more complex regular expression that accounts for optional whitespace.

Why it fails: While a single regular expression with \s* can tolerate optional whitespace, it quickly becomes an unreadable monolith that must encode every possible output variation into one pattern, including header lines, blank lines, and wrapped entries. Any new field or format change requires rewriting the entire regex, and debugging state across a line-by-line stream is still not handled cleanly. TextFSM manages this through smaller per-line regexes with named captures and state transitions, making it far more maintainable.

Reduce the collection frequency to every 4 hours

Why it fails: Lowering the collection interval to every 4 hours does not address the underlying cause of the timeout. The script still iterates through 500 devices sequentially within a single run, so the total execution time remains unchanged and will still exceed any fixed timeout threshold. This change merely reduces how often the problem occurs, not the problem itself, and could degrade monitoring granularity.

Replace Netmiko with SNMP polling using the pysnmp library

Why it fails: Switching to SNMP polling with pysnmp changes the data-collection paradigm entirely: SNMP requires every router to have an SNMP agent configured with community strings or credentials, and it can only return OIDs defined in MIBs, not arbitrary CLI output or show commands. While SNMP GETs are lightweight and could be parallelized, the missing metrics or the need to rewrite the entire collection logic makes this a non-trivial replacement that does not directly solve the existing timeout issue. It also adds operational overhead for SNMP configuration and security policy.

Use Ansible playbooks instead of a custom Python script

Why it fails: Ansible can parallelize device connections using the 'forks' parameter, but a default of 5 concurrent forks is often insufficient for 500 devices, and the control node's SSH connection handling can still hit timeout or performance bottlenecks. The playbook approach also shifts to a different automation framework, requiring inventory management and YAML task definitions, and does not inherently fix the root cause—the need for concurrent connections. If forks are not explicitly increased and connection timeout values not tuned, the same timeout behavior will persist.

All translations are static NAT entries.

Why it fails: Static NAT entries are manually configured and persist in the translation table indefinitely, regardless of traffic. The provided output shows no such persistence evidence: every entry is accompanied by an idle timer context, and several entries carry TCP/UDP port numbers, which static NAT never creates. Static NAT would never mix port-based translations with portless ones, so the statement that all translations are static is false.

The router is performing only PAT (overload).

Why it fails: If the router were performing only PAT (overload), every translation would include a protocol field and port numbers in the inside local/inside global columns, because PAT multiplexes many inside hosts onto a single outside address. The output, however, contains a portless one-to-one translation for 10.0.0.10, which cannot occur with pure PAT. Additionally, the outside global addresses are not all the same; a single overloaded interface would reuse one public IP for all translations, so the observed diversity of outside global addresses contradicts this option.

The outside global address is the same for all translations.

Why it fails: The translation table clearly lists different outside global addresses: 203.0.113.5 is used in some entries, while 198.51.100.2 appears in others. If every translation shared the same outside global address, the configuration would have to be a single-address pool or one overloaded interface. Since the output shows at least two distinct outside global addresses, the statement that the outside global address is the same for all translations is incorrect.