5 Protocols, Services, and Ports Free Online FlashCards

What is a network service?

A service is a function provided to applications, such as resolving a domain name or delivering a web page.

What does a port identify on a host?

A port identifies an application endpoint on a host. IP addresses help deliver traffic to the host; TCP or UDP ports help deliver it to the service.

What delivery does TCP provide?

TCP provides a connection-oriented, reliable, ordered byte stream, using acknowledgments and retransmission to recover from lost data.

What delivery guarantees does UDP provide?

UDP sends independent datagrams without guaranteeing delivery, ordering, or duplicate protection. Applications may add reliability themselves.

Which details commonly identify a network flow?

A flow is commonly identified by its source and destination IP addresses and port numbers, plus the transport protocol.

What does DNS do, and what port does it generally use for queries?

DNS resolves names such as example.com to data such as IP addresses. It generally uses UDP port 53 for queries and responses.

When might DNS use TCP port 53?

DNS uses TCP port 53 when a connection is needed, including for some large responses and zone transfers.

What configuration can DHCP provide to a host?

DHCP automatically provides network configuration, such as an IP address, subnet mask, default gateway, and DNS server.

Which UDP ports do the IPv4 DHCP client and server use?

In the familiar IPv4 exchange, the DHCP client sends from UDP port 68 to the server on UDP port 67.

What does DORA stand for in DHCP?

DORA stands for Discover, Offer, Request, Acknowledge—the common sequence of a DHCP exchange.

What is HTTP's conventional port and communication model?

HTTP transfers web resources using a request-and-response model. Its conventional port is TCP 80.

How does HTTPS protect HTTP, and which transports use port 443?

HTTPS is HTTP protected with TLS, which provides encryption and authentication. Its conventional port is TCP 443; HTTP/3 uses QUIC over UDP 443.