Methods and apparatus to use client-server communications across internet domains to determine distributed demographic information for media impressions

A non-transitory computer-readable medium comprising instructions that, when executed, cause processor circuitry to at least:

• generate a first message for a first server of a first Internet domain in response to detecting a login event at a client device in association with an Internet-based service of a second Internet domain, the second Internet domain outside the first Internet domain;
• access a second message from the first server of the first Internet domain, the second message including a global unique identifier (GUID) and a login timestamp, the GUID identifying at least one of the client device or a user of the client device to the first Internet domain;
• and
• generate a third message including (a) the GUID, (b) a cookie identifier associated with the second Internet domain, and (c) the login timestamp, the third message to cause generation of an identifier-to-cookie map at a second server of the second Internet domain.

An apparatus comprising:

• memory;
• instructions;
• and
• processor circuitry to execute the instructions to:
• send a first message to a first server of a first Internet domain in response to detecting a login event at a client device in association with an Internet-based service of a second Internet domain, the second Internet domain outside the first Internet domain;
• access a second message from the first server of the first Internet domain, the second message including a global unique identifier (GUID) and a login timestamp, the GUID identifying at least one of the client device or a user of the client device to the first Internet domain;
• and
• generate a third message including (a) the GUID, (b) a cookie identifier associated with the second Internet domain, and (c) the login timestamp, the third message to cause generation of an identifier-to-cookie map at a second server of the second Internet domain.