1. Measurement Capabilities

CAIDA shall deploy and operate Ark node(s) configured to perform a comprehensive suite of network measurement functions, which include those listed below. Ideally, the firewall serving the node is configured without rate-limiting. Note that hosting sites may opt out of measurements other than those described in Section (a) Topology Measurements, below, in negotiation with CAIDA.

1.1. Topology Measurements (MANDATORY)

• ICMP: Hosting site will forward ICMP packets from Ark nodes for topology and delay assessments, and will accept ICMP responses.
• UDP: In support of UDP-based topology measurements, hosting site will forward protocol-compliant UDP probes from any local port on the Ark node to any host and any port. These UDP probes do not solicit UDP responses – they solicit ICMP responses.
• TCP Measurements: Hosting site will forward TCP probes from any local port on the Ark node to any host and port, regardless of connection state.

1.2. DNS Measurements: Hosting site will allow Ark nodes to send DNS queries to a locally configured DNS server and to external DNS servers (including root servers, global TLD servers, and other public servers) to study performance, security (e.g., DNSSEC validation), and protocol evolution.

1.3. UDP (non-topology) Measurements: Hosting site will allow Ark nodes to send arbitrary protocol-compliant UDP packets as required to support measurement activities.

1.4. HTTP/HTTPS Measurements: Hosting site will allow Ark nodes to conduct protocol-compliant HTTP and HTTPS transactions—including TLS handshakes and content analyses—to evaluate performance metrics, e.g., handshake latency, security features, CDN behavior, and network load distribution.

1.5. IP Spoofing Measurements: Hosting site will support controlled IP spoofing techniques for Reverse Traceroute and security assessments (such as RPKI/ROV evaluations). CAIDA will configure strict technical safeguards to ensure minimal risk.

2. CAIDA Obligations and Commitments

2.1 Data Collection, Management, and Remote Administration: CAIDA will be responsible for the remote management of the Ark node(s): software, configuration, security patching, upgrades, and management of user accounts. If the hosting site requires local administrative access, CAIDA will provide a system administration account upon written request. The Ark Host shall not use the Ark node for activities unrelated to the purposes of CAIDA measurements and in particular for any activities that may damage other persons or networks in any way.

2.2 Data Sharing: CAIDA may make collected and derivative data publicly available.

2.3 Ethical Conduct and Operational Best Practices: CAIDA and vetted collaborators will conduct measurement activities in accordance with prevailing industry standards and research community best practices. CAIDA will enforce reasonable limits on measurement frequency and volume, and maintain a “no probe” list to honor opt-out requests.

2.4 Complaint Resolution and Compliance: CAIDA will promptly address any complaints regarding measurement activities forwarded by the Hosting Site and will cooperate in resolving any issues by adjusting measurement configurations or updating the no probe list as necessary.

3. Hosting Site Obligations and Requirements

3.1 Provision of Physical Space and Operational Support: The Hosting Site agrees to allocate and maintain sufficient space for the installation, deployment, and continuous operation of one or more Ark nodes. The hosting site agrees to provide (on occasion) “remote hands” services to address issues at the system console that cannot be resolved remotely by CAIDA.

3.2 Maintenance Notifications and Network Configurations: The Hosting Site shall inform CAIDA in advance of any planned maintenance or incidents that may disrupt power or network availability, whenever possible, to allow CAIDA to perform a controlled shutdown of the Ark node(s) if needed.

3.3 Communication and Contact Information: The Hosting Site shall designate a primary email address and a physical mailing address for Ark node-related communications and coordination, and communicate changes of this information to CAIDA.

4. Risk Mitigation and Indemnification

4.1 Risk Acknowledgment: Despite adherence to industry best practices and the implementation of technical safeguards, the operation of Ark node(s) involves inherent risks, even if the measurement activities are designed to be benign and respectful of operational concerns and risks.

4.2 Indemnification: Each Party agrees to indemnify, defend, and hold harmless the other Party (including its officers, employees, and agents) from and against any claims, losses, damages, liabilities, and expenses (including reasonable attorneys’ fees) arising from any collecting of measurement data, services, or outputs provided through the Ark node operations.

4.3 Disclaimer of Warranties and Limitation of Liability: CAIDA operates the Ark nodes, related software, and any measurement data, services, or outputs provided through them on an “as is” basis, without any express or implied warranties of merchantability, fitness for a particular purpose, accuracy, timeliness, completeness, reliability, or availability.

5. Termination

This MOC shall remain in effect until terminated by either Party for any reason by providing written (email) notice to the other party. Upon termination, the Parties shall confer in good faith to determine the disposition of any CAIDA-provided hardware, either by returning it to CAIDA or disposing of it using a mutually agreed-upon procedure. CAIDA is entitled to maintain copies of data collected from the host’s node and make them publicly available.

6. General Provisions

This MOC, together with any exhibits or attachments, constitutes the entire agreement between the Parties concerning its subject matter and supersedes all prior agreements or understandings, whether written or oral.

7. Governing Jurisdiction

This MOC shall be governed by and construed in accordance with the laws of the State of California, United States, without regard to its conflict of law principles.

Contact and Acknowledgment

If you, as the Hosting Site, agree to the terms and conditions set forth in this MOC, please complete the acknowledgment form provided by CAIDA and supply the required contact information for further coordination regarding the deployment and operation of an Ark node. For any questions, concerns, or requests for further clarification regarding this MOC or its implementation, please contact CAIDA at

Complete the form to host an Ark monitor

If you are interested in hosting an Ark node, please complete the form below acknowledging the MOC along with some contact information so we can follow up with you about sending you an Ark node to deploy.