Cisco ENCOR 350-401 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Collapsed core

A two-tier design where the core and distribution layers are combined into one layer. Access switches connect directly to the collapsed core pair.

LISP in SD-Access

Provides the control plane for the SD-Access fabric by mapping endpoint identifiers (EIDs) to routing locators (RLOCs). It separates identity from location.

CAPWAP ports

The control channel uses UDP 5246 and the data channel uses UDP 5247. The AP establishes both tunnels to the WLC during discovery and join.

FlexConnect local switching

An AP mode where client data traffic is switched locally at the AP rather than tunneled to the WLC. Useful for branch survivability if the WAN fails.

SSO vs NSF

SSO keeps both control-plane and data-plane state during supervisor failover. NSF keeps forwarding while the control plane restarts, using graceful protocol restart.

802.3bt PoE

The PoE standard that defines Type 3 (up to 60 W at the PSE) and Type 4 (up to 90 W). Earlier standards are 802.3af (15.4 W) and 802.3at (30 W).

Type 1 hypervisor

A hypervisor that runs directly on the physical hardware without an underlying host OS. Examples include VMware ESXi and Microsoft Hyper-V.

VRF-lite

Virtual routing and forwarding without MPLS. Multiple independent routing tables exist on one router, and interfaces are assigned with the ip vrf forwarding command.

VXLAN VNI size

VXLAN uses a 24-bit VNI, allowing roughly 16 million segments. Frames are encapsulated in UDP with destination port 4789 between VTEPs.

GRE overhead

A GRE tunnel adds 24 bytes of header overhead and provides no encryption. It can carry multicast and non-IP traffic, unlike plain IPsec tunnels.

SD-Access border node

The fabric node that connects the fabric to external networks such as the WAN or Internet. It often peers with a fusion router for shared services.

Containers vs VMs

Containers share the host kernel and are lighter and faster to start. VMs include a full guest OS, giving stronger isolation but lower density.

OSPF hello timers

On broadcast and point-to-point networks the hello interval is 10 seconds and the dead interval is 40 seconds. NBMA uses 30 and 120 seconds.

OSPF cost formula

Cost equals the reference bandwidth divided by the interface bandwidth. The default reference bandwidth is 100 Mbps, so a FastEthernet link costs 1.

EIGRP feasible successor

A backup route whose reported distance is less than the current feasible distance of the successor. It can be used immediately without recomputation.

BGP weight

The first attribute in BGP best-path selection. It is Cisco-proprietary, local to the router, and higher values are preferred.

RSTP alternate port

An RSTP port role that provides an alternate path to the root bridge. It can transition to forwarding quickly when the root port fails.

HSRP virtual MAC

HSRP uses the virtual MAC 0000.0c07.acXX, where XX is the group number in hex. VRRP uses 0000.5e00.01XX instead.

PAT overload

A NAT configuration where many inside local addresses share one or a few inside global addresses, distinguished by source port numbers.

LLQ

Low Latency Queuing gives a strict priority queue to latency-sensitive traffic such as voice, while CBWFQ guarantees bandwidth to other classes.

Syslog severity 0-7

Severity levels run from 0 (emergency) to 7 (debugging); lower numbers are more severe. A configured logging level includes that level and all lower numbers.

SNMPv3 security

Version 3 adds authentication using MD5 or SHA and privacy using DES or AES. Versions 1 and 2c rely only on plaintext community strings.

ERSPAN

Encapsulated Remote SPAN tunnels mirrored traffic in GRE across a Layer 3 network to a destination. RSPAN instead carries the traffic over a dedicated VLAN.

IP SLA tracking

IP SLA probes measure latency, jitter, and loss. Tracking objects bind the probe results to static routes, HSRP, or other features for failover.

EEM applet

An Embedded Event Manager script that triggers on an event such as a syslog message, SNMP trap, or timer and then runs CLI actions.

RADIUS vs TACACS+

RADIUS uses UDP 1812/1813 and encrypts only the password. TACACS+ uses TCP 49 and encrypts the entire payload, separating authentication and authorization.

802.1X roles

The supplicant is the endpoint, the authenticator is the switch port, and the authentication server is typically a RADIUS server. EAPoL runs between supplicant and authenticator.

Port security violation modes

Protect drops and logs silently. Restrict drops, logs, and increments a counter. Shutdown puts the port in err-disabled state.

DHCP snooping trust

Only ports facing the legitimate DHCP server are trusted. Untrusted ports cannot offer DHCP replies, preventing rogue servers and feeding DAI and IP Source Guard.

IPsec AH vs ESP

AH provides integrity and authentication but no confidentiality. ESP provides confidentiality plus integrity and is the usual choice for site-to-site VPNs.

NETCONF transport

NETCONF runs over SSH on TCP port 830 and exchanges XML-encoded data. Operations include get-config, edit-config, lock, and commit.

RESTCONF methods

GET reads data, POST creates, PUT replaces, PATCH merges, and DELETE removes. Data is encoded in JSON or XML and modeled by YANG.