2 Protocols and Ports Free Online FlashCards

What does a network port identify?

A port identifies an application or service on a device. An IP address, transport protocol, and port together help identify a particular network endpoint.

What delivery does TCP provide?

TCP establishes a connection and provides reliable, ordered delivery of a byte stream. It retransmits lost data.

What does DNS do, and which port is commonly associated with it?

DNS resolves domain names to records such as IP addresses. Ordinary queries commonly use UDP port 53; DNS also uses TCP port 53 when needed.

What does SMTP do, and which ports are commonly associated with it?

SMTP sends or relays outgoing email. TCP port 25 commonly handles server-to-server transfer; ports 587 and 465 commonly serve message submission.

Why does a familiar port number not prove which service is running?

A familiar port is a useful clue to traffic purpose, not proof. Services can use nonstandard ports, and port numbers can be reassigned or misused.

Where can you check registered port numbers authoritatively?

The IANA registry is the authoritative reference for registered port numbers.

What delivery guarantees does UDP provide?

UDP sends independent datagrams with less transport overhead, but it does not guarantee delivery, ordering, or duplicate protection.

What configuration does DHCP provide, and which UDP ports are used?

DHCP automatically provides network configuration, such as an IP address, default gateway, and DNS server. Its server commonly uses UDP port 67 and its client UDP port 68.

What is HTTP used for, and what is its traditional port?

HTTP transfers web requests and responses. Traditional HTTP commonly uses TCP port 80.

How does HTTPS protect web traffic, and what transport may HTTP/3 use?

HTTPS carries web traffic with encryption and server authentication. It commonly uses TCP port 443; HTTP/3 runs over QUIC, which uses UDP.

What service is commonly associated with TCP port 22?

SSH provides encrypted remote login and other secure network services, including command-line administration and file transfer. It commonly uses TCP port 22.

How does POP3 retrieve email, and what is its implicit-TLS port?

POP3 retrieves email from a mailbox, often by downloading messages to a client. It commonly uses TCP port 110; port 995 is POP3 with implicit TLS.