Huawei HCIA-Datacom flashcards

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

TCP three-way handshake

Connection setup uses SYN, SYN-ACK, and ACK segments; it synchronizes sequence numbers and confirms that both endpoints are reachable before data transfer begins.

UDP characteristics

Connectionless transport protocol with no handshake, acknowledgments, or retransmission; low overhead and used for DNS, DHCP, TFTP, SNMP, and real-time traffic.

ARP function

Resolves an IPv4 address to a MAC address on the local link by broadcasting a request and caching the unicast reply in the ARP table.

Well-known port numbers

FTP uses 20 and 21, SSH 22, Telnet 23, HTTP 80, HTTPS 443, DNS 53, DHCP 67 and 68, SNMP 161 and 162, and NTP 123.

Private IPv4 ranges

10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are non-routable on the Internet and are used inside private networks behind NAT.

Longest prefix match

A router forwarding an IPv4 packet selects the route with the most specific prefix, meaning the longest subnet mask, among all routes that match the destination address.

Huawei default route preference

Lower preference values are preferred; directly connected routes use 0, OSPF internal 10, static 60, RIP 100, OSPF external 150, and BGP 255.

OSPF hello and dead timers

On broadcast and point-to-point networks the default hello interval is 10 seconds and the dead interval is 40 seconds; both must match for adjacency formation.

OSPF DR and BDR

On a broadcast multi-access segment, routers elect a Designated Router and Backup Designated Router to reduce adjacencies and LSA flooding; highest priority wins, then highest router ID.

802.1Q VLAN tag

A 4-byte tag inserted into an Ethernet frame that carries a 12-bit VLAN identifier, allowing up to 4094 usable VLANs over a trunk link.

Access and trunk ports

An access port carries one VLAN and connects end devices; a trunk port carries multiple VLANs, tagging frames with 802.1Q except optionally the native VLAN.

STP root bridge election

Switches elect the root bridge with the lowest bridge ID, composed of bridge priority and MAC address; the default priority is 32768.

RSTP port states

Rapid Spanning Tree Protocol uses three states: discarding, learning, and forwarding, replacing the five states of classic STP for faster convergence.

LACP aggregation modes

Link Aggregation Control Protocol has active and passive modes; active initiates LACPDUs, passive responds, and at least one side must be active to form an Eth-Trunk.

DHCP DORA process

Clients obtain addresses through Discover, Offer, Request, and Acknowledge messages; the server uses UDP port 67 and the client uses UDP port 68.

NAPT

Network Address Port Translation, also called PAT or NAT overload, maps many private IP addresses to one public address by translating source port numbers.

AAA components

Authentication verifies user identity, authorization grants permissions and services, and accounting records resource usage and activity for auditing.

RADIUS ports

RADIUS servers use UDP port 1812 for authentication and authorization and UDP port 1813 for accounting; Huawei devices can act as RADIUS clients.

Advanced ACL range

Huawei advanced ACLs are numbered 3000 to 3999 and can match source and destination IP addresses, protocol, source and destination ports, and TCP flags.

PPP authentication protocols

Password Authentication Protocol sends passwords in clear text, while Challenge Handshake Authentication Protocol uses a challenge-response hash and is more secure.

PPPoE sessions

PPPoE has a discovery stage that establishes a session ID and a session stage that carries PPP frames over Ethernet, commonly used for broadband access.

SNMP ports and roles

SNMP managers query agents on UDP port 161 and receive notifications or traps on UDP port 162; MIB objects are identified by OIDs.

Syslog severity levels

Syslog defines eight severity levels from 0 emergency to 7 debugging; lower numbers are more severe, and messages are sent to UDP port 514.

SSH versus Telnet

SSH uses TCP port 22 and encrypts the management session, while Telnet uses TCP port 23 and transmits credentials and data in clear text.

TFTP characteristics

Trivial File Transfer Protocol uses UDP port 69, provides no authentication or encryption, and supports simple file upload and download with minimal overhead.

IPv6 address length

An IPv6 address is 128 bits long, written as eight hexadecimal groups; leading zeros in a group and one continuous run of zero groups may be compressed.

IPv6 link-local address

Link-local addresses begin with FE80::/10, are automatically configured on every IPv6 interface, and are used for neighbor discovery and next-hop communication on a link.

IPv6 neighbor discovery

ND uses Router Solicitation and Advertisement plus Neighbor Solicitation and Advertisement messages to discover routers, resolve link-layer addresses, and detect duplicate addresses.

IPv6 DHCPv6 flags

In Router Advertisement messages, the M flag tells hosts to use stateful DHCPv6 for addresses, and the O flag tells them to use DHCPv6 for other configuration.

SDN three-layer architecture

SDN separates the application, control, and data planes; a centralized controller programs forwarding devices through southbound interfaces and exposes services northbound.

VXLAN VNI

VXLAN uses a 24-bit VXLAN Network Identifier in an 8-byte header, supporting about 16 million logical networks; traffic is encapsulated in UDP port 4789.

NETCONF transport

NETCONF uses XML-encoded RPC messages, typically over SSH on TCP port 830, and models device data with YANG for configuration and state retrieval.