Use Advanced Search to bypass hostname resolution and use a custom IP address or port.

Address
Host

heizungsfragen.de

QUIC is supported

HTTP/3 is supported

HTTP/3 Check established a QUIC connection for all attempts made with the given endpoint. See the metrics below for more information.

0-RTT

Zero Round Trip Time Resumption (0-RTT)

The QUIC handshake for this connection was completed without any additional round-trips.

SUCCESS
h3

QUIC Versions

These are the QUIC versions supported by this QUIC endpoint.

AGREED SUPPORTED
Connection ID

Connection ID

This unique identifier for a QUIC connection is used to ensure that changes to an endpoint's lower network layer address (UDP/IP) does not affect the delivery of the QUIC connection's packets.

This tool attempts two connections to test the server's 0-RTT capabilities. During the first connection, the client receives important handshake material from the server. With 0-RTT, the client can start to send data immediately if it uses this handshake material when it creates the second connection.

Packet RX

Packet RX

This value represents the time between the first packet sent and the first packet received (measured in milliseconds).

Handshake Done

Handshake Done

This value represents the time between when the first packet is sent and when the handshake is completed (measured in milliseconds).

Take notice of the difference in this metric between the first connection and the second connection. Using 0-RTT, future connections (i.e. the second connection) can complete the handshake much faster than the original connection.

1242964D3F... 92.8 185.021
25A5309EB6... 91.217 91.561

Read detailed descriptions of the items and metrics shown above.

HTTP/3 Statistics

Zero Round Trip Time Resumption (0-RTT)

The QUIC handshake for this connection was completed without any additional round-trips.

SUCCESS

QUIC Versions

These are the QUIC versions supported by this QUIC endpoint.

AGREED SUPPORTED

Connection ID

This unique identifier for a QUIC connection is used to ensure that changes to an endpoint's lower network layer address (UDP/IP) does not affect the delivery of the QUIC connection's packets.

This tool attempts two connections to test the server's 0-RTT capabilities. During the first connection, the client receives important handshake material from the server. With 0-RTT, the client can start to send data immediately if it uses this handshake material when it creates the second connection.


Packet RX

This value represents the time between the first packet sent and the first packet received (measured in milliseconds).


Handshake Done

This value represents the time between when the first packet is sent and when the handshake is completed (measured in milliseconds).

Take notice of the difference in this metric between the first connection and the second connection. Using 0-RTT, future connections (i.e. the second connection) can complete the handshake much faster than the original connection.


QLog

QLog is a standard under development for QUIC Connection debugging and visualization. Learn more at https://quic.edm.uhasselt.be/

To view or download the raw QLog ("application/json"), add "format=qlog" to the HTTP query string.

HTTP Header

HTTP/1.1 200 OK
server: nginx
date: Thu, 05 Mar 2026 14:54:31 GMT
content-type: text/html; charset=UTF-8
vary: accept-encoding
vary: Accept-Encoding
set-cookie: heizungsfragen_user_session=74b1e48f7b14e00c1e9e9e5e3b343f12f22ca9b8390e9addaf4426aa3b08f49d-AeC3Th%2FRIzjFDDbdymFRQ%2BUYEmTrJQ%3D%3D; path=/; domain=heizungsfragen.de; secure; HttpOnly
x-content-type-options: nosniff
x-frame-options: SAMEORIGIN
set-cookie: XSRF-TOKEN=47cd0dafd7e1b7c4c726074af9a62d2fae59a7617f92b5d08144135d13edaa09-0CmqeYN6ZhCD31xb1C%2BHqg%3D%3D; path=/; secure
last-modified: Thu, 05 Mar 2026 14:54:31 GMT
cache-control: max-age=0, no-cache, no-store, must-revalidate
x-xss-protection: 1; mode=block
x-permitted-cross-domain-policies: master-only
referrer-policy: same-origin
alt-svc: h3=":443"; ma=86400
x-xss-protection: 1; mode=block
permissions-policy: camera=(), geolocation=(), microphone=(), payment=(), interest-cohort=()
strict-transport-security: max-age=31536000; includeSubDomains; preload
referrer-policy: same-origin
cross-origin-opener-policy: same-origin
cross-origin-resource-policy: same-site
content-security-policy: upgrade-insecure-requests

Certificate Chain

Domain heizungsfragen.de
Issued By R13
Expires Sunday, May 31, 2026 at 04:19:21 PM GMT
This certificate is valid
Subject
Common Name heizungsfragen.de
Issuer
Country US
Organization Let's Encrypt
Common Name R13
Serial Number 460617284613277445469863331818992135466790
Signature Algorithm sha256WithRSAEncryption
Version
Public Key Bits 4096
Public Key Type RSA

Domain R13
Issued By ISRG Root X1
Expires Friday, March 12, 2027 at 11:59:59 PM GMT
Subject
Country US
Organization Let's Encrypt
Common Name R13
Issuer
Country US
Organization Internet Security Research Group
Common Name ISRG Root X1
Serial Number 119635429456979344322213464088047616773
Signature Algorithm sha256WithRSAEncryption
Version
Public Key Bits 2048
Public Key Type RSA

Domain ISRG Root X1
Issued By ISRG Root X1
Expires Monday, June 04, 2035 at 11:04:38 AM GMT
Subject
Country US
Organization Internet Security Research Group
Common Name ISRG Root X1
Issuer
Country US
Organization Internet Security Research Group
Common Name ISRG Root X1
Serial Number 172886928669790476064670243504169061120
Signature Algorithm sha256WithRSAEncryption
Version
Public Key Bits 4096
Public Key Type RSA

QLog Output

QLog

QLog is a standard under development for QUIC Connection debugging and visualization. Learn more at https://quic.edm.uhasselt.be/

To view or download the raw QLog ("application/json"), add "format=qlog" to the HTTP query string.

{
  "qlog_version": "0.1",
  "description": "heizungsfragen.de",
  "connections": [
    {
      "qlog_version": "0.1",
      "vantagepoint": "NETWORK",
      "connectionid": "1242964D3F6FC0D2",
      "starttime": 12640892498199,
      "fields": [
        "time",
        "category",
        "type",
        "trigger",
        "data"
      ],
      "events": [
        [
          0,
          "CONNECTIVITY",
          "NEW_CONNECTION",
          "LINE",
          {
            "ip_version": "6",
            "srcip": "::",
            "dstip": "2a01:239:0:805b::1",
            "srcport": "40794",
            "dstport": "443"
          }
        ],
        [
          60,
          "CONNECTIVITY",
          "VERNEG",
          "LINE",
          {
            "proposed_version": "00000001"
          }
        ],
        [
          92800,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "c900000001081242964d3f6fc0d2140000000000001043698f941fb0b7c51f...",
            "header": {
              "type": "INIT",
              "payload_length": "138",
              "packet_number": "0"
            },
            "frames": [
              {
                "frame_type": "ACK"
              },
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          92805,
          "CONNECTIVITY",
          "VERNEG",
          "PACKET_RX",
          {
            "agreed_version": "00000001"
          }
        ],
        [
          93080,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "eb00000001081242964d3f6fc0d2140000000000001043698f941fb0b7c51f...",
            "header": {
              "type": "HSK",
              "payload_length": "1030",
              "packet_number": "0"
            },
            "frames": [
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          93236,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "e700000001081242964d3f6fc0d2140000000000001043698f941fb0b7c51f...",
            "header": {
              "type": "HSK",
              "payload_length": "1184",
              "packet_number": "1"
            },
            "frames": [
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          93443,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "ed00000001081242964d3f6fc0d2140000000000001043698f941fb0b7c51f...",
            "header": {
              "type": "HSK",
              "payload_length": "1184",
              "packet_number": "2"
            },
            "frames": [
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          184620,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "e100000001081242964d3f6fc0d2140000000000001043698f941fb0b7c51f...",
            "header": {
              "type": "HSK",
              "payload_length": "380",
              "packet_number": "3"
            },
            "frames": [
              {
                "frame_type": "ACK"
              },
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          184705,
          "SECURITY",
          "CHECK_CERT",
          "CERTLOG",
          {
            "certificate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
          }
        ],
        [
          184705,
          "SECURITY",
          "CHECK_CERT",
          "CERTLOG",
          {
            "certificate": "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"
          }
        ],
        [
          185021,
          "CONNECTIVITY",
          "HANDSHAKE",
          "PACKET_RX",
          {
            "status": "complete"
          }
        ],
        [
          276244,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "4a1242964d3f6fc0d24b21ada6aeef1eb74d02d5fa2df043edc2dca9e9e8e7...",
            "header": {
              "type": "SHORT",
              "payload_length": "889",
              "packet_number": "0"
            },
            "frames": [
              {
                "frame_type": "STREAM"
              },
              {
                "frame_type": "ACK"
              },
              {
                "frame_type": "NEW_CONNECTION_ID"
              },
              {
                "frame_type": "CRYPTO"
              },
              {
                "frame_type": "HANDSHAKE_DONE"
              }
            ]
          }
        ],
        [
          293394,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "5a1242964d3f6fc0d2a6b426926c03940344387aa047490b5751fa35df929a...",
            "header": {
              "type": "SHORT",
              "payload_length": "841",
              "packet_number": "1"
            },
            "frames": [
              {
                "frame_type": "STREAM"
              }
            ]
          }
        ]
      ]
    },
    {
      "qlog_version": "0.1",
      "vantagepoint": "NETWORK",
      "connectionid": "25A5309EB6246F91",
      "starttime": 12640892792038,
      "fields": [
        "time",
        "category",
        "type",
        "trigger",
        "data"
      ],
      "events": [
        [
          0,
          "CONNECTIVITY",
          "NEW_CONNECTION",
          "LINE",
          {
            "ip_version": "6",
            "srcip": "::",
            "dstip": "2a01:239:0:805b::1",
            "srcport": "40794",
            "dstport": "443"
          }
        ],
        [
          34,
          "CONNECTIVITY",
          "VERNEG",
          "LINE",
          {
            "proposed_version": "00000001"
          }
        ],
        [
          91217,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "cf000000010825a5309eb6246f911400000000000010432caab49b81b39748...",
            "header": {
              "type": "INIT",
              "payload_length": "144",
              "packet_number": "0"
            },
            "frames": [
              {
                "frame_type": "ACK"
              },
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          91221,
          "CONNECTIVITY",
          "VERNEG",
          "PACKET_RX",
          {
            "agreed_version": "00000001"
          }
        ],
        [
          91486,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "eb000000010825a5309eb6246f911400000000000010432caab49b81b39748...",
            "header": {
              "type": "HSK",
              "payload_length": "1024",
              "packet_number": "0"
            },
            "frames": [
              {
                "frame_type": "PADDING"
              },
              {
                "frame_type": "CRYPTO"
              }
            ]
          }
        ],
        [
          91561,
          "CONNECTIVITY",
          "HANDSHAKE",
          "PACKET_RX",
          {
            "status": "complete"
          }
        ],
        [
          91590,
          "RECOVERY",
          "RTT_UPDATE",
          "PACKET_RX",
          {
            "zero_rtt": "successful"
          }
        ],
        [
          366448,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "5225a5309eb6246f91fbe4e65fd2341d7b81381f570032fb897d178aa7e99f...",
            "header": {
              "type": "SHORT",
              "payload_length": "603",
              "packet_number": "0"
            },
            "frames": [
              {
                "frame_type": "STREAM"
              },
              {
                "frame_type": "ACK"
              },
              {
                "frame_type": "NEW_CONNECTION_ID"
              },
              {
                "frame_type": "CRYPTO"
              },
              {
                "frame_type": "HANDSHAKE_DONE"
              }
            ]
          }
        ],
        [
          384340,
          "TRANSPORT",
          "PACKET_RX",
          "LINE",
          {
            "raw": "4125a5309eb6246f913efef4f3619a0b3b6d5d0f7fa10958d6a4c13af165fe...",
            "header": {
              "type": "SHORT",
              "payload_length": "836",
              "packet_number": "1"
            },
            "frames": [
              {
                "frame_type": "STREAM"
              }
            ]
          }
        ]
      ]
    }
  ]
}