If they've contributed to your taxable income in a meaningful way through earned revenue (parking, developed sites etc), they'll likely be considered assets and assigned a value.
If there is a history of domain sales contributing to your taxable income in a meaningful way, they'll likely be considered assets and assigned a value.
If there is a very evident high worth to the domains (super premium domains that are easily recognisable as being valuable), they'll likely be considered assets and assigned a value. Original purchase price may be used to establish a baseline/starting point for valuation.
I've never been through a divorce, so I can only make assumptions, but I imagine that it would ultimately be a question of magnitude and what other assets, finances etc are being negotiated. Any item that has significantly contributed to income or has a clear high value is likely to be included in negotiations (depending on any prenuptial agreements etc).