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Difficulty: MediumNetworking Ports and Protocols

A network administrator is documenting ingress and egress port rules for an organization's network edge. Match each networking protocol on the left with its correct default port and transport protocol on the right.

  • LDAP (Lightweight Directory Access Protocol)TCP Port 389
  • POP3 (Post Office Protocol v3)TCP Port 110
  • NetBIOS Session ServiceTCP Port 139
  • SNMP (Simple Network Management Protocol)UDP Port 161

Answer

LDAP matches TCP Port 389; POP3 matches TCP Port 110; NetBIOS Session Service matches TCP Port 139; SNMP matches UDP Port 161.
Each service correctly aligns with its standardized IANA port mapping and transport protocol: LDAP uses TCP 389 for directory lookups, POP3 uses TCP 110 for unencrypted mail retrieval, NetBIOS Session Service uses TCP 139 for legacy session management, and SNMP uses UDP 161 for device monitoring queries.

Step-by-Step Solution

1
Identify the primary function and default protocol assignment for directory services.
LDAP is used for directory queries over TCP port 389.
Lightweight Directory Access Protocol defaults to unencrypted TCP port 389.
2
Identify the unencrypted email retrieval protocol port.
POP3 operates over TCP port 110.
Post Office Protocol version 3 uses TCP port 110 (whereas encrypted POP3S uses TCP 995).
3
Determine the port for NetBIOS Session Service.
NetBIOS Session Service operates on TCP port 139.
NetBIOS Name Service uses UDP 137, Datagram Service uses UDP 138, and Session Service uses TCP 139.
4
Determine the port and transport mechanism for SNMP querying.
SNMP operates over UDP port 161.
Simple Network Management Protocol relies on connectionless UDP port 161 for device polling (SNMP traps use UDP 162).

Key Concept

Networking Ports and Protocols
Estimated Time:1m 0s
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Topics

Networking Ports and Protocols

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